Year 9 Cambridge Computer Science Unit Test Mock Paper Analysis | 九年级剑桥计算机单元测试模拟卷解析

📚 Year 9 Cambridge Computer Science Unit Test Mock Paper Analysis | 九年级剑桥计算机单元测试模拟卷解析

This article walks you through a complete Year 9 Cambridge-style unit test mock paper, offering detailed explanations for every question. Working through these solutions will strengthen your understanding of core computing topics, from binary arithmetic to network security, and help you identify typical exam pitfalls before the real assessment.

本文带你逐题解析一份九年级剑桥风格计算机单元测试模拟卷，并为每一道题提供详细讲解。通过研读这些解析，你将加深对二进制运算、网络安全等核心计算机主题的理解，并在正式评估前识别常见考试陷阱。

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1. Converting Binary to Decimal | 二进制转十进制

Question: Convert the binary number 110010 to its decimal equivalent. Show your working using the place-value table.

题目：将二进制数 110010 转换为十进制。借助位值表展示计算过程。

The place values in an 8‑ ch column and sum those where the digit is 1: 32 + 16 + 2 = 50. Therefore, 110010₂ = 50₁₀.

8位二进制系统的位值从左到右分别为128、64、32、16、8、4、2、1。对于二进制数00110010，将每一位数字填入对应列，然后把数字为1的位值相加：32 + 16 + 2 = 50。所以，110010₂ = 50₁₀。

Place value	128	64	32	16	8	4	2	1
Binary digit	0	0	1	1	0	0	1	0

A common mistake is to treat the leftmost '1' as carrying the value 64 or 128 without extending to 8 bits. Always align the least significant bit with the units column.

一个常见错误是未将二进制数扩展为8位，就误以为最左边的“1”代表64或128。务必始终将最低有效位与个位列对齐。

110010₂ = 32 + 16 + 2 = 50₁₀

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2. Logic Gates and Truth Tables | 逻辑门与真值表

Question: ed into a NAND gate. State the output. Also draw the truth table for a two-input NOR gate.

题目：输入A = 1，B = 0进入一个与非门（NAND）。写出输出结果。同时，画出两输入或非门（NOR）的真值表。

e lists all input combinations and shows that the output is 1 only when both inputs are 0.

与非门的输出是与门结果的反相。与门(1,0) = 0，因此与非门(1,0) = 1。或非门真值表列出所有输入组合，并显示只有当两个输入都为0时，输出才为1。

NOR Gate Truth Table | 或非门真值表

A	B	Output
0	0	1
0	1	0
1	0	0
1	1	0

Remember the NOR truth table by saying 'Not OR' – the output is true only when neither A nor B is true.

记住或非门真值表的一个口诀是“既非A亦非B”——只有当A和B都不为真时，输出才为真。

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3. Flowchart Symbol Identification & Trace | 流程图符号识别与追踪

Question: Identify the following flowchart symbols and explain their purpose: a diamond, a parallelogram, and a rectangle. Then trace the given flowchart that adds user-entered numbers until a zero is entered, and state the output if the inputs are 5, 3, 0.

题目：识别以下流程图符号并说明用途：菱形、平行四边形、矩形。然后追踪给定的流程图：将用户输入的数字累加，直到输入零为止；若输入依次为5、3、0，请写出输出结果。

arithmetic or assignment. Tracing the loop: the sum initialises to 0; input 5 → sum = 5; input 3 → sum = 8; input 0 → the condition 'input = 0?' becomes true, so the loop ends and the sum 8 is output.

菱形表示判断（是/否分支），平行四边形代表输入/输出操作，矩形表示处理过程，例如算术运算或赋值。追踪循环：总和初始为0；输入5 → 总和 = 5；输入3 → 总和 = 8；输入0 → 条件“输入=0?”为真，循环终止，输出总和8。

Flowcharts are a visual way to design algorithms; make sure you can distinguish between the four basic symbols to avoid logic errors in your own programs.

流程图是设计算法的可视化方式；务必能区分四种基本符号，以避免自己编写的程序出现逻辑错误。

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4. Python Code Tracing (Loops) | Python代码追踪（循环）

Question: What is printed by the following Python code?

for i in range(3):
    print(i * 2)

题目：以下Python代码会打印什么？

The range(3) generates the values 0, 1, and 2. In each iteration, the variable i takes one of these values, and the print statement outputs i * 2. Therefore, the output is 0, 2, and 4 on separate lines.

range(3) 生成数值 0、1 和 2。每次循环中，变量 i 依次取这些值，打印语句输出 i * 2 的结果。因此输出为分行显示的 0、2 和 4。

Output: 0 → 2 → 4

A typical mistake is to think range(3) starts at 1 or includes 3. Remember: Python's range(n) produces integers from 0 up to n−1.

一个典型错误是认为 range(3) 从1开始或包含3。请记住：Python 的 range(n) 产生从0到n−1的整数。

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5. Data Storage Units | 数据存储单位

Question: Convert 3 gigabytes (GB) into megabytes (MB) and then into kilobytes (KB). Express the final answer in standard form.

题目：将3千兆字节（GB）转换为兆字节（MB），再转换为千字节（KB）。最终答案用标准形式表示。

ientific notation) this is 3.145728 × 10⁶ KB. (Some exam boards accept 1000 as the multiplier for simplicity; here we use the binary definition as per Cambridge IGCSE/O Level.)

在数据存储中，1 GB = 1024 MB，1 MB = 1024 KB。因此，3 GB = 3 × 1024 = 3072 MB。然后 3072 MB = 3072 × 1024 = 3,145,728 KB。用标准形式（科学记数法）表示为 3.145728 × 10⁶ KB。（部分考纲为简化采用1000作为乘数；此处按剑桥 IGCSE/O Level 使用二进制定义。）

3 GB = 3072 MB = 3,145,728 KB ≈ 3.15 × 10⁶ KB

Always check which conversion factor your syllabus specifies. Even if you use 1000, the method remains the same; only the numeric result differs.

一定要查看你所学大纲指定的换算系数。即使使用1000，方法也完全相同，只是数值结果不同。

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6. Network Topologies: Star vs. Bus | 网络拓扑结构：星型与总线型

Question: Compare a star network topology with a bus topology. Give one advantage and one disadvantage of each.

题目：比较星型网络拓扑和总线型拓扑。各给出一个优点和一个缺点。

In a star topology, all devices connect to a central hub or switch. An advantage is that if one cable fails, only that device is affected; a disadvantage is that the central device is a single point of failure. In a bus topology, all devices share a single backbone cable. An advantage is its low cost and simple setup; a disadvantage is that if the backbone breaks, the entire network goes down.

在星型拓扑中，所有设备都连接到中央集线器或交换机。优点是如果某条电缆损坏，只有该设备受影响；缺点是中央设备为单点故障。在总线型拓扑中，所有设备共享一条主干电缆。优点是成本低且安装简单；缺点是如果主干断裂，整个网络将瘫痪。

Modern home and school networks predominantly use a star or extended star topology because it offers greater reliability and easier troubleshooting.

现代家庭和学校网络主要采用星型或扩展星型拓扑，因为它提供更高的可靠性和更便捷的故障排查。

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7. Internet Protocols | 互联网协议

Question: Explain the difference between HTTP and HTTPS. Also state the role of TCP/IP in data transmission.

题目：解释 HTTP 与 HTTPS 的区别。并说明 TCP/IP 在数据传输中的作用。

HTTP (HyperText Transfer Protocol) transfers web pages between a server and a client, but the data is sent in plain text. HTTPS adds a layer of encryption using SSL/TLS, so the communication is secure and cannot be easily intercepted. TCP/IP is the foundational protocol suite of the internet: TCP breaks data into packets and ensures they are reassembled correctly, while IP handles addressing and routing these packets across networks.

HTTP（超文本传输协议）在服务器与客户端之间传输网页，但数据以明文发送。HTTPS 通过 SSL/TLS 增加了一层加密，因此通信是安全的，不易被截获。TCP/IP 是互联网的基础协议族：TCP 将数据拆分成数据包并确保正确重组，IP 则负责这些数据包在网络中的寻址和路由。

Always look for the padlock icon in your browser to check whether you are using HTTPS, especially when entering personal information.

请始终留意浏览器中的挂锁图标，以确认自己正在使用 HTTPS，尤其是在输入个人信息时。

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8. Cybersecurity: Phishing | 网络安全：网络钓鱼

Question: Define phishing and describe two signs that an email might be a phishing attempt.

题目：定义网络钓鱼，并描述两个表明某封邮件可能是网络钓鱼企图的迹象。

Phishing is a social engineering attack where criminals send deceptive emails or messages pretending to be a trustworthy entity in order to steal sensitive data such as passwords or credit card details. Signs of a phishing email include: (1) urgent or threatening language pressuring you to act quickly, and (2) generic greetings like 'Dear customer' instead of your name.

网络钓鱼是一种社会工程攻击，犯罪分子发送欺骗性邮件或消息，冒充可信任实体，以窃取密码或信用卡信息等敏感数据。网络钓鱼邮件的迹象包括：（1）使用紧急或威胁性语言催促你立即行动；（2）使用“尊敬的客户”等通用问候语，而非你的姓名。

Never click on suspicious links. If in doubt, contact the organisation directly through their official website rather than using the link provided in the email.

切勿点击可疑链接。如有疑问，请通过官方渠道直接联系相关机构，而不是使用邮件中提供的链接。

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9. Algorithm Tracing: Bubble Sort | 算法追踪：冒泡排序

Question: Show the state of the list [5, 3, 8, 1] after the first pass of a bubble sort (ascending order). Explain each comparison and swap.

题目：展示列表 [5, 3, 8, 1] 经过冒泡排序（升序）第一趟之后的状态。解释每一次比较和交换。

8 → no swap. Compare 8 and 1 → swap, list becomes [3, 5, 1, 8]. The largest element, 8, has bubbled to the end of the list. The list after the first pass is [3, 5, 1, 8].

冒泡排序比较相邻元素并在顺序错误时交换它们。第一趟：比较5和3 → 交换，列表变为 [3, 5, 8, 1]；比较5和8 → 不交换；比较8和1 → 交换，列表变为 [3, 5, 1, 8]。最大元素8已“冒泡”到列表末尾。第一趟之后列表为 [3, 5, 1, 8]。

Tracing algorithms manually is a key skill. Keep a pencil-and-paper record of each step to avoid losing track of the current list state.

手动追踪算法是一项关键技能。用纸笔记录每一个步骤，以免混淆当前的列表状态。

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10. Ethical and Legal Issues in Computing | 计算机中的伦理与法律问题

Question: A student copies the entire text from a website and submits it as their own work. Name this offense and explain one way it can be prevented. Also, describe the term 'copyright' in this context.

题目：某学生从网站复制全部文本并作为自己的作业提交。指出这种违规行为的名称，并解释一种预防方法。同时，在此语境下描述“版权”一词的含义。

The offense is called plagiarism – presenting someone else's work or ideas as your own without proper acknowledgment. One prevention method is to use plagiarism-detection software, which compares submitted work against a vast database of online content. Copyright is the legal right that grants the creator of original work exclusive control over its use and distribution; copying without permission infringes this right.

这种违规行为称为抄袭——在未适当注明出处的情况下将他人的作品或观点呈现为自己的。一种预防方法是使用抄袭检测软件，它会将提交的作业与庞大的在线内容数据库进行比对。版权是一种法律权利，赋予原创作品的创作者对其使用和分发的专有控制权；未经许可复制即侵犯了该权利。

Understanding intellectual property is essential not only for exams but also for your future academic and professional life. Always cite your sources.

理解知识产权不仅对考试至关重要，也对未来的学术与职业生涯意义重大。请务必注明出处。

Published by TutorHao | Computer Science Revision Series | aleveler.com

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