📚 Summer Preparation and Bridging Course for Year 11 OCR Computer Science | Year 11 OCR 计算机科学暑期预习与衔接课程
A well-structured summer bridging plan makes the transition to Year 11 smoother and builds confidence in tackling OCR GCSE Computer Science. This article guides you through every major topic area, blending revision of Year 10 fundamentals with an early look at the deeper concepts you will meet in Year 11. By following the paired English–Chinese explanations and practical suggestions, you can reinforce your understanding and get ahead before the new academic year begins.
一份精心安排的暑期衔接计划能让 Year 11 的过渡更平稳，并建立应对 OCR 计算机科学考试的信心。本文将带你梳理所有核心主题，融合对 Year 10 基础的回顾以及对 Year 11 更深层次概念的提前接触。通过中英对照的讲解和实用建议，你可以在新学年开始前巩固理解、抢占先机。
1. How to Use This Summer Bridging Programme | 如何用好这份暑期衔接方案
Start by auditing your confidence in each topic from the Year 10 curriculum. Identify areas that felt shaky and allocate more time to them. The paired English–Chinese paragraphs are designed so you can read the English explanation first to grasp the technical vocabulary required by OCR, then read the Chinese version to ensure deep conceptual understanding.
首先，对 Year 10 课程中的每个主题进行信心自评。找出那些你感觉不扎实的领域，并为其分配更多时间。中英对照段落的设计意图是：先读英文解释来掌握 OCR 要求的技术词汇，再读中文版以确保概念理解透彻。
Keep a vocabulary log of key terms such as 'von Neumann architecture', 'virtual memory', 'SQL injection' and 'logic gate'. Every time you meet a new term in the English paragraph, write it down together with its Chinese equivalent and a one-line definition. Active recall with these logs mirrors the questioning style of the exam papers and strengthens your bilingual command of computer science language.
为“冯·诺依曼架构”、“虚拟内存”、“SQL 注入”、“逻辑门”等关键术语建立词汇日志。每次在英文段落中遇到新术语，就把它和对应的中文及一句话定义记录下来。用这些日志进行主动回忆，既能模拟试卷的提问风格，又能增强你对计算机科学语言的双语掌握。
Finally, each week set a small project: write pseudocode for a familiar algorithm, draw the logic circuit for a simple Boolean expression, or explain how packet switching works to a family member. These active outputs turn passive reading into lasting knowledge.
最后，每周设定一个小任务：为你熟悉的算法写伪代码，为简单的布尔表达式绘制逻辑电路，或者向家人解释数据包交换的工作原理。这些主动输出能把被动阅读转化为持久的知识。
2. Overview of the OCR J277 Specification and Assessment | OCR J277 大纲与评估概览
The OCR GCSE (9–1) in Computer Science (J277) is split into two examined components. Component 01, 'Computer Systems', covers systems architecture, memory and storage, networks, network security, systems software, and ethical, legal, cultural and environmental concerns. It is assessed through a 1 hour 30 minutes written paper worth 50 % of the total marks.
OCR GCSE (9–1) 计算机科学（J277）分为两个笔试部分。第一部分“计算机系统”涵盖系统架构、内存与存储、网络、网络安全、系统软件，以及伦理、法律、文化和环境问题，采用 1 小时 30 分钟的笔试，占总分的 50%。
Component 02, 'Computational Thinking, Algorithms and Programming', focuses on algorithms, programming techniques, producing robust programs, Boolean logic, and programming languages and IDEs. This paper also lasts 1 hour 30 minutes and counts for the remaining 50 % of the marks. Both papers require you to apply knowledge to novel scenarios, not just recall facts.
第二部分“计算思维、算法与编程”聚焦算法、编程技术、编写可靠程序、布尔逻辑以及编程语言与集成开发环境。该卷同为 1 小时 30 分钟，占余下 50% 的分数。两份试卷都要求你把知识应用于新情境，而非仅仅回忆事实。
Bridging successfully means understanding the command words. 'State' requires a short factual answer, 'describe' asks for characteristics, 'explain' demands reasoning about cause and effect, and 'discuss' expects a balanced evaluation. Throughout this article, we will model answers that match these expectations.
成功衔接意味着理解指令词。“State”要求给出简短的事实性回答，“describe”要求描述特征，“explain”要求推导因果关系，“discuss”则需要进行平衡的评估。本文中我们将用符合这些要求的回答进行示范。
3. Systems Architecture: CPU and Embedded Systems | 系统架构：CPU 与嵌入式系统
The Central Processing Unit (CPU) is often called the 'brain' of the computer. It continuously follows the fetch–decode–execute cycle: the control unit fetches an instruction from memory, the instruction is decoded to determine what needs to be done, and the arithmetic logic unit (ALU) executes it. Any change to the speed of this cycle affects overall performance.
中央处理器常被称为计算机的“大脑”。它不断执行“取指–译码–执行”循环：控制单元从内存中取出指令，对指令进行译码以确定需要做什么，然后由算术逻辑单元执行。该循环速度的任何变化都会影响整体性能。
The von Neumann architecture stores both program instructions and data in the same memory unit, connected to the CPU via buses. The address bus carries memory location identifiers, the data bus transfers the actual data or instructions, and the control bus transmits timing and control signals. Understanding this architecture helps explain why memory speed and bus widths are critical bottlenecks.
冯·诺依曼架构将程序指令和数据存放在同一个内存单元中，通过总线与 CPU 相连。地址总线传送存储位置标识，数据总线传输实际的数据或指令，控制总线则发送时序与控制信号。理解这一架构有助于解释为什么内存速度和总线宽度是关键瓶颈。
Three main factors influence CPU performance: clock speed, cache size, and number of cores. A higher clock speed means more fetch–decode–execute cycles per second, but it also generates more heat. Larger cache memory reduces the average time to access data from the main memory (RAM), while multiple cores allow genuine parallel processing of instructions—especially beneficial when running several applications at once.
影响 CPU 性能的三个主要因素是：时钟频率、缓存大小和核心数量。更高的时钟频率意味着每秒可完成更多次取指–译码–执行循环，但也会产生更多热量。更大的缓存能减少访问主存（RAM）的平均时间，而多核则允许真正并行处理指令——这在同时运行多个应用时尤其有利。
An embedded system is a dedicated computer built into a larger device, such as a washing machine, microwave, or car engine control unit. It typically runs a single program stored in ROM, consumes very little power, and is optimised for reliability. On the OCR exam, you may need to contrast embedded systems with general-purpose desktop computers.
嵌入式系统是内嵌在更大设备中的专用计算机，例如洗衣机、微波炉或汽车发动机控制单元。它通常只运行一个存储在 ROM 中的程序，功耗极低，并且为高可靠性而优化。在 OCR 考试中，你可能需要对比嵌入式系统与通用桌面计算机。
4. Memory, Storage and Data Representation | 内存、存储与数据表示
Random Access Memory (RAM) is volatile main memory that holds the operating system, programs, and data currently in use. When the power is turned off, all data in RAM is lost. Read Only Memory (ROM) is non-volatile; it stores the bootstrap loader and firmware needed when the computer first starts up. The more RAM a system has, the more applications and files it can keep open without slowing down.
随机存取内存是易失性主存，保存着正在使用的操作系统、程序和数据。断电后 RAM 中的所有数据都会丢失。只读存储器是非易失性的，它存储着计算机初次启动时所需的引导程序和固件。系统拥有的 RAM 越多，能同时打开的应用和文件就越多，并且不会减慢速度。
Virtual memory is a technique that uses part of the hard disk or SSD as if it were extra RAM. When RAM is full, pages of idle data are moved to virtual memory so that the active program can continue. However, because secondary storage is far slower than RAM, excessive reliance on virtual memory causes thrashing and noticeably degrades performance.
虚拟内存是一种把部分硬盘或固态硬盘当作额外 RAM 来使用的技术。当 RAM 已满，空闲数据页面会被移到虚拟内存中，使活跃程序能继续运行。然而，由于二级存储器远慢于 RAM，过度依赖虚拟内存会导致系统抖动，明显降低性能。
All data inside a computer is represented in binary (1s and 0s). Numbers can be stored as unsigned binary, and characters are encoded using character sets such as ASCII or Unicode. The Unicode standard can represent characters from almost all the world's writing systems, using up to 32 bits per character, which explains why a document in multiple languages uses more storage than plain ASCII text.
计算机内部所有数据都以二进制（1 和 0）表示。数字可以用无符号二进制存储，字符则使用如 ASCII 或 Unicode 这样的字符集编码。Unicode 标准能表示世界上几乎所有书写系统的字符，每个字符最多使用 32 位，这解释了为什么多语言文档比纯 ASCII 文本占用更多存储空间。
Images are stored as grids of pixels. In a bitmap, each pixel is assigned a binary code representing its colour; the colour depth (bits per pixel) determines how many colours can be represented. Higher resolution and colour depth increase image quality but also inflate file size. Sound is sampled at regular intervals, and each sample is given a binary value—the sample rate and bit depth combine to influence both audio fidelity and storage requirements.
图像以像素网格的形式存储。在位图中，每个像素分配一个代表其颜色的二进制码；色深（每像素位数）决定了能表示多少种颜色。更高的分辨率和色深能提升图像质量，但也会增大文件体积。声音以固定间隔进行采样，每个样本被给一个二进制值——采样率和位深共同影响音频保真度和存储需求。
Data compression can be lossless, where no information is lost (e.g., run-length encoding for simple images, or ZIP files for text), or lossy, where some data is permanently removed to achieve much smaller sizes (e.g., JPEG for photos, MP3 for music). For a summer activity, try using Python to write a simple run-length encoding algorithm and observe how the compressed output changes with different inputs.
数据压缩可以是无损的，即不丢失任何信息（例如针对简单图像的游程编码，或文本的 ZIP 文件），也可以是有损的，即永久移除部分数据以达到更小的体积（例如照片的 JPEG、音乐的 MP3）。作为暑期活动，你可以尝试用 Python 编写一个简单的游程编码算法，观察不同输入下压缩输出的变化。
5. Computer Networks, Connections and Protocols | 计算机网络、连接与协议
A network is two or more computers connected together to share resources and data. Local Area Networks (LANs) operate over a small geographical area, such as a school or office, and are typically owned by a single organisation. Wide Area Networks (WANs) span larger distances and connect LANs together; the internet is the largest WAN.
网络是由两台或以上计算机连接在一起，用以共享资源和数据。局域网覆盖较小地理区域，如学校或办公室，通常由单个组织拥有。广域网横跨更大距离，连接多个局域网；互联网就是最大的广域网。
Client–server and peer-to-peer are the two main network models. In a client–server network, a central server stores files and manages security, while clients request services. In a peer-to-peer model, each computer acts as both client and server, which works well for direct file sharing but can be less secure.
客户端–服务器和对等网络是两种主要网络模型。在客户端–服务器网络中，中央服务器存储文件并管理安全，客户机请求服务。在对等模型中，每台计算机既是客户端又是服务器，适合直接文件共享，但安全性可能较差。
Network hardware includes the Network Interface Card (NIC), which provides the physical address (MAC address) for each device, switches that intelligently forward frames to the correct destination, and routers that direct packets between different networks using IP addresses. When you browse a website, multiple routers work together to deliver packets from the web server to your device.
网络硬件包括：网卡，为每个设备提供物理地址（MAC 地址）；交换机，智能地将帧转发到正确目的地；路由器，使用 IP 地址在不同网络之间引导数据包。当你浏览网页时，多个路由器协同工作，将数据包从网络服务器传送到你的设备。
The internet relies on the TCP/IP protocol stack, a layered model that separates concerns. The application layer handles user-facing protocols such as HTTP, HTTPS, FTP and SMTP. The transport layer uses TCP to guarantee reliable delivery or UDP for faster, connectionless transmission. The internet layer (IP) handles addressing and routing, while the link layer manages the physical transmission of bits.
互联网依赖 TCP/IP 协议栈这一分层模型，将不同关注点分离。应用层处理面向用户的协议，如 HTTP、HTTPS、FTP 和 SMTP。传输层使用 TCP 保证可靠传输，或使用 UDP 实现更快、无连接的传输。网络层（IP）负责寻址与路由，链路层则管理比特的物理传输。
A protocol is simply a set of rules that govern how data is transmitted. HTTP is the protocol for transferring web pages, HTTPS adds encryption via SSL/TLS, FTP transfers files, POP/IMAP retrieve emails, and SMTP sends them. You can deepen your summer revision by using a network protocol analyser such as Wireshark to observe real packets in action, always on a network you have permission to monitor.
协议不过是一套管理数据传输的规则。HTTP 是传输网页的协议，HTTPS 通过 SSL/TLS 添加加密，FTP 传输文件，POP/IMAP 检索电子邮件，SMTP 则负责发送。你可以通过使用 Wireshark 等网络协议分析器观察真实数据包来深化暑期复习，务必在获准监控的网络上进行。
6. Network Security: Threats and Prevention | 网络安全：威胁与防护
Malware is malicious software designed to damage or gain unauthorised access to a computer system. Viruses attach themselves to legitimate files and spread when those files are shared, while worms self-replicate without needing a host. Trojans disguise themselves as useful software but carry hidden malicious payloads. Spyware secretly monitors user activity, and ransomware encrypts files to demand payment.
恶意软件是旨在损害或未经授权访问计算机系统的恶意软件。病毒附着在合法文件上，并在文件共享时传播；蠕虫无需宿主就能自我复制。木马伪装成有用的软件，却携带隐藏的恶意负载。间谍软件秘密监控用户活动，勒索软件则加密文件以索要赎金。
Social engineering attacks manipulate people into revealing confidential information. Phishing involves deceptive emails or messages that appear to come from trusted sources, tricking recipients into providing passwords or bank details. Blagging (pretexting) invents a believable scenario to extract data, and shouldering (shoulder surfing) simply means watching someone type their credentials.
社会工程攻击通过操纵人来获取机密信息。网络钓鱼涉及看似来自可信来源的欺骗性邮件或消息，诱使收件人提供密码或银行信息。虚假借口编造可信场景以套取数据，而肩窥就是直接观看他人输入凭据。
Brute-force and denial-of-service (DoS) attacks target system availability. A brute-force attack repeatedly tries credentials until access is granted; limiting login attempts and enforcing strong passwords are effective countermeasures. DoS attacks flood a server with traffic to overwhelm it; firewalls and intrusion prevention systems help filter out malicious requests.
暴力破解和拒绝服务攻击针对系统的可用性。暴力破解反复尝试凭据直至获得访问权限；限制登录尝试次数并强制使用强密码是有效的对策。DoS 攻击用流量淹没服务器使其瘫痪；防火墙和入侵防御系统有助于过滤掉恶意请求。
SQL injection occurs when an attacker inserts malicious SQL statements into a web form input, manipulating the database behind the site. Prevention relies on input sanitisation, parameterised queries, and strong validation of all user-supplied data. Cross-site scripting (XSS) injects scripts into web pages viewed by others; proper output encoding and content security policies reduce the risk.
SQL 注入发生在攻击者将恶意 SQL 语句插入网页表单输入，从而操纵网站后台数据库时。防御依赖于输入清理、参数化查询以及对所有用户提供数据的严格验证。跨站脚本将脚本注入他人浏览的网页；正确的输出编码和内容安全策略可降低风险。
Every secure system combines multiple layers. Penetration testing simulates attacks to find vulnerabilities. Anti-malware software detects known threats via signature databases and behavioural analysis. Firewalls filter incoming and outgoing traffic using rules, and encryption—such as WPA3 for Wi-Fi—protects data as it travels. User access controls enforce the principle of least privilege, granting only the permissions necessary for a task.
每个安全系统都结合了多个层次。渗透测试模拟攻击以查找漏洞。反恶意软件通过特征库和行为分析检测已知威胁。防火墙使用规则过滤出入流量，而加密——如 Wi-Fi 的 WPA3——在数据传输过程中保护数据。用户访问控制则贯彻最小权限原则，仅授予完成任务所必需的权限。
7. Systems Software: Operating Systems and Utility Software | 系统软件：操作系统与实用工具
An operating system (OS) is the fundamental software that manages hardware and provides services for application programs. Its key functions include memory management (allocating RAM to different processes), processor scheduling (deciding which process runs next), file management (organising files into directories and controlling access rights), and managing input/output devices through drivers.
操作系统是管理硬件并为应用程序提供服务的底层软件。其主要功能包括：内存管理（为不同进程分配 RAM）、处理器调度（决定下一个运行的进程）、文件管理（将文件组织到目录中并控制访问权限）以及通过驱动程序管理输入/输出设备。
The user interface provided by the OS can be graphical (GUI), command-line (CLI), menu-driven or even natural language. GUI is widely used because icons, windows and pointers make interaction intuitive, whereas CLI gives advanced users greater control and scripting capabilities. For OCR, be able to explain why a CLI might be chosen over a GUI, for example when remote management requires low bandwidth.
操作系统提供的用户界面可以是图形化界面、命令行界面、菜单驱动甚至自然语言界面。图形化界面广受欢迎，因为图标、窗口和指针让交互变得直观，而命令行界面为高级用户提供了更大的控制权和脚本能力。在 OCR 考试中，你需要解释为什么有时会选择 CLI 而非 GUI，例如在远程管理需要低带宽时。
Utility software carries out maintenance and security tasks. Disk defragmentation reorganises fragmented files on a magnetic hard disk so that each file occupies contiguous blocks, improving read times—this is not needed on SSDs because they have no moving parts. Encryption utilities, such as full-disk encryption, protect data if a device is lost. Backup utilities automate the creation of copies, and compression utilities reduce file size for storage or transmission.
实用工具软件执行维护与安全任务。磁盘碎片整理将机械硬盘上碎片化的文件重新组织，使每个文件占据连续数据块，从而缩短读取时间——固态硬盘不需要这样做，因为它没有移动部件。加密实用工具，如全盘加密，在设备丢失时保护数据。备份工具自动创建副本，压缩工具则减小文件体积以便存储或传输。
te a table that matches each utility to the user problem it solves. For instance, problem: 'Computer runs very slowly after many months of heavy use' entation. This cause-and-effect thinking will directly prepare you for application questions on Paper 1.
复习时，可以制作一张表格，将每个实用工具与它解决的用户问题配对。例如，问题：“电脑在重度使用数月后运行极慢”→ 解决方案：磁盘清理与碎片整理。这种因果思维能直接帮助你应对 Paper 1 中的应用题。
8. Ethical, Legal, Cultural and Environmental Impacts | 伦理、法律、文化及环境影响
Digital technology raises profound ethical questions. Stakeholder analysis requires you to consider how a new technology—such as facial recognition in public spaces—affects privacy, fairness, and accountability. OCR examiners expect you to weigh the convenience and security benefits against the risk of mass surveillance and bias in training data.
数字技术引发了深刻的伦理问题。利益相关者分析要求你思考一项新技术——比如公共场所的面部识别——如何影响隐私、公平性和问责性。OCR 考官希望你能权衡便利与安全的好处，以及大规模监控和训练数据偏差带来的风险。
The Data Protection Act 2018 (which mirrors GDPR principles) stipulates that personal data must be collected for specified purposes, be accurate, kept no longer than necessary, and processed securely. When answering questions about online services, explicitly refer to these principles and relate them to concepts such as consent, subject access requests, and the right to erasure.
《2018 年数据保护法》（体现 GDPR 原则）规定，个人数据必须为指定目的收集、保持准确、保存时间不超过必要且被安全处理。在回答关于在线服务的题目时，要明确引用这些原则，并将其与同意、主体访问请求以及删除权等概念联系起来。
Computer Misuse Act 1990 makes unauthorised access to computer material, intent to commit further offences, and unauthorised modification of data (including malware distribution) illegal. Copyright, Designs and Patents Act 1988 protects creators' rights over software, music, and digital art; using someone else's code without a suitable open-source licence can breach this law.
《1990 年计算机滥用法》将未经授权访问计算机材料、意图进一步犯罪以及未经授权修改数据（包括传播恶意软件）定为非法。《1988 年版权、设计和专利法》保护创作者对软件、音乐和数字艺术的权利；在缺少适当开源许可证的情况下使用他人代码可能违反该法律。
Open source software allows anyone to view, modify and distribute the source code, fostering community collaboration but often lacking a dedicated support team. Proprietary software keeps the source code secret; users pay for a licence and receive regular updates and professional support. When evaluating software choices, organisations must consider total cost of ownership, security transparency, and availability of customisation.
开源软件允许任何人查看、修改和分发源代码，促进社区协作，但往往缺少专属支持团队。专有软件则对源代码保密；用户购买许可后能获得定期更新和专业支持。在评估软件选择时，组织必须考虑总拥有成本、安全透明度以及定制化的可能性。
The environmental impact of computing is increasingly examined. Data centres consume enormous amounts of electricity for servers and cooling, while e-waste from discarded devices pollutes the environment if not recycled properly. Students should be ready to discuss how virtualisation, cloud computing consolidation, and energy-efficient processors can mitigate these effects, as well as the role of the WEEE directive and responsible recycling schemes.
计算对环境的影响越来越多地受到考察。数据中心为服务器和冷却消耗巨量电力，而废弃设备产生的电子垃圾若未妥善回收则会污染环境。学生应能讨论虚拟化、云计算整合以及节能处理器如何减轻这些影响，还应了解 WEEE 指令与负责任回收计划的作用。
9. Algorithms: Thinking and Designing Solutions | 算法：思维与方案设计
An algorithm is a step-by-step procedure for solving a problem. Two essential searching algorithms are linear search, which inspects each item in turn until the target is found or the list ends, and binary search, which repeatedly halves a sorted list. Binary search is far more efficient on large datasets with O(log n) complexity, but it can only work on sorted data.
算法是用于解决问题的一步一步的过程。两种基本的搜索算法是：线性搜索，逐个检查每一项直到找到目标或列表结束；二分查找，反复将已排序列表一分为二。二分查找在大数据集上效率高得多，具有 O(log n) 的复杂度，但它只能在有序数据上工作。
Sorting algorithms include bubble sort, which repeatedly passes through the list swapping adjacent items if they are in the wrong order, and insertion sort, which builds a sorted sublist by taking elements one by one. For visual understanding, draw a trace table that tracks the state of the list after each pass; this is a skill OCR examiners expect you to demonstrate.
排序算法包括：冒泡排序，不断遍历列表并在相邻元素顺序错误时交换它们；插入排序，通过逐个取出元素来构建有序子列表。为加深理解，可绘制追踪表来记录每次遍历后列表的状态；这是 OCR 考官希望你展示的技能。
Flowcharts and pseudocode are the two main ways to represent algorithms. Flowcharts use standard symbols—ovals for start/stop, rectangles for processes, diamonds for decisions—to show the flow of control visibly. Pseudocode uses structured English-like statements; OCR has its own reference language you should practise, including INPUT, OUTPUT, IF... THEN... ELSE... ENDIF, and FOR... TO... NEXT loops.
流程图和伪代码是表示算法的两种主要方式。流程图使用标准符号——椭圆形用于起止，矩形用于处理，菱形用于判断——直观地展示控制流。伪代码则采用结构化的类英语语句；你应该练习使用 OCR 自己的参考语言，包括 INPUT、OUTPUT、IF... THEN... ELSE... ENDIF 以及 FOR... TO... NEXT 循环。
When solving algorithmic problems, you must also identify and correct errors. A logic error produces an unexpected output; a syntax error breaks the rules of the language. Trace through your algorithm using sample data, and verify the output against expected results. Explaining this debugging process clearly can score highly on extended response questions.
在解决算法问题时，你还必须识别并纠正错误。逻辑错误产生意外输出；语法错误则违反语言规则。用样本数据逐行追踪你的算法，并将输出与预期结果比对。清晰地解释这一调试过程能在拓展回答题中获得高分。
10. Programming Fundamentals: Data Types, Control Flow and Arrays | 编程基础：数据类型、控制流与数组
Every programming language provides fundamental data types: integer, real (or float), Boolean (true/false), character, and string. Choosing the correct data type affects memory usage and the operations that can be performed. For instance, adding two integers works mathematically, but adding two strings concatenates them—distinctions OCR will test in code-reading exercises.
所有编程语言都提供基本数据类型：整型、实型（浮点型）、布尔型（真/假）、字符和字符串。选择正确的数据类型会影响内存占用及可执行的操作。例如，两个整型相加进行数学运算，但两个字符串相加则进行拼接——OCR 会在读代码练习中考查这些区别。
onstants for fixed values such as VAT_RATE improves code readability and maintenance. Adopt meaningful naming conventions—for example, use 'studentName' rather than 's'—to make your pseudocode self-documenting.
变量是命名的内存位置，用于存储值。常量类似变量，但初始化后值不能改变；将固定值（如 VAT_RATE）定义为常量能提高代码可读性和可维护性。采用有意义的命名约定——例如用 'studentName' 而不用 's'——让你的伪代码具有自文档化特性。
Program flow is controlled with sequence, selection, and iteration. Selection uses IF, ELSE IF, and ELSE statements to branch based on conditions. Iteration can be count-controlled (FOR loops) or condition-controlled (WHILE and REPEAT... UNTIL). Nested structures, where a loop exists inside another selection or loop, are common in real-world programs and appear regularly in exam tasks.
程序流通过顺序、选择和迭代来控制。选择使用 IF、ELSE IF 和 ELSE 语句根据条件分支。迭代可以是计数控制（FOR 循环）或条件控制（WHILE 和 REPEAT... UNTIL）。嵌套结构——即循环位于另一选择或循环内部——在真实世界程序中很常见，也经常出现在考试任务中。
Arrays (or lists in some languages) store multiple items of the same data type under one identifier, with each element accessed by an index. A two-dimensional array is like a grid with rows and columns, useful for representing chess boards, exam marks, or pixel matrices. Practise traversing a 2D array using nested FOR loops to perform operations like summing each row or finding the maximum value.
数组（某些语言中称为列表）用一个标识符存储多个同类型的数据项，每个元素通过索引访问。二维数组就像有行和列的网格，常用于表示棋盘、考试成绩或像素矩阵。练习用嵌套 FOR 循环遍历二维数组，执行诸如将每一行求和或寻找最大值
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