📚 Year 7 WJEC Computer Science: In-depth Analysis of Past Papers | 七年级 WJEC 计算机：历年真题深度解析
This article provides a detailed walkthrough of common past paper questions for Year 7 WJEC Computer Science. Each section presents a typical exam-style question, followed by step-by-step explanations of the concepts and the most effective ways to approach the answer. Mastering these patterns will build your confidence and help you secure high marks in assessments.
本文深度解析七年级 WJEC 计算机历年真题中的常见题型。每个小节呈现一道典型的考试风格题目，然后逐步解释背后的概念及解题技巧。掌握这些模式将帮助你建立信心，在考试中取得高分。
1. Binary to Denary Conversion | 二进制与十进制转换
Example question: Convert the binary number 1101 to denary. Show your working.
示例题目： 将二进制数 1101 转换为十进制。写出你的计算过程。
To convert from binary to denary, write down the place values for each bit. For a 4‑bit binary number the column headings are 8, 4, 2 and 1. Then add the values of all columns that contain a 1.
要从二进制转换为十进制，先写出每一位的位权值。四位二进制数的列标题依次是 8、4、2 和 1。然后将所有包含“1”的列的数值相加。
(1 × 4) + (0 × 2) + (1 × 1) = 8 + 4 + 0 + 1 = 13. Therefore, the denary equivalent is 13.
对于 1101，计算过程为：(1 × 8) + (1 × 4) + (0 × 2) + (1 × 1) = 8 + 4 + 0 + 1 = 13。所以十进制等值为 13。
A common mistake is to read the binary number from right to left incorrectly. Always align the least significant bit (rightmost) with the 1 column. In longer binary numbers you expand the place values: 128, 64, 32, 16, 8, 4, 2, 1.
常见错误是搞错从右向左的位权对齐。始终让最低有效位（最右边）对应于 1 这一列。更长的二进制数只需扩展位权值：128, 64, 32, 16, 8, 4, 2, 1。
2. Denary to Binary Conversion | 十进制与二进制转换
Example question: Represent the denary number 25 as an 8‑bit binary number.
示例题目： 将十进制数 25 表示为一个 8 位二进制数。
One reliable method is the division‑by‑2 method. Repeatedly divide the number by 2 and record the remainder. The binary digits are the remainders read from bottom to top.
一种可靠的方法是“除二取余法”。不断将数字除以 2 并记录余数。二进制数字就是将这些余数从下往上读取。
2 = 1 remainder 1; 1 ÷ 2 = 0 remainder 1. Reading remainders upwards gives 11001. As an 8‑bit number, pad with leading zeros: 00011001.
25 ÷ 2 = 12 余 1；12 ÷ 2 = 6 余 0；6 ÷ 2 = 3 余 0；3 ÷ 2 = 1 余 1；1 ÷ 2 = 0 余 1。从下往上读取余数得到 11001。作为 8 位二进制数，前面补零：00011001。
Another approach is to use the place value table. Start from the largest value (128) and ask: does 25 contain this value? Work rightwards. You will place a 1 under 16, 8 and 1, giving the same result.
另一种方法是使用位权表格。从最大值（128）开始，问 25 是否包含该值？向右逐渐判断。最终在 16、8 和 1 下方填入 1，得到相同结果。
3. Identifying Hardware Components | 识别硬件组件
Example question: Match each component to its description: CPU, RAM, Hard Disk Drive, Motherboard.
示例题目： 将下列组件与其功能描述配对：CPU、RAM、硬盘驱动器、主板。
| Component | Description |
| CPU | Executes instructions and carries out calculations |
| RAM | Stores data and programs currently in use, volatile |
| Hard Disk Drive | Long‑term, non‑volatile storage of files and software |
| Motherboard | The main circuit board that connects all components |
The CPU (Central Processing Unit) is often called the 'brain' of the computer. It fetches, decodes and executes instructions. RAM (Random Access Memory) is temporary working memory that loses its contents when the power is off, so it is volatile. The hard disk drive provides permanent storage for the operating system, applications and user files.
CPU（中央处理器）常被称为计算机的“大脑”。它负责取指令、译码和执行。RAM（随机存取存储器）是临时的工作内存，断电后内容丢失，因此是易失性的。硬盘驱动器为操作系统、应用程序和用户文件提供永久存储。
When answering matching questions, read all descriptions carefully before making a choice. Look for keywords such as 'volatile', 'long‑term' and 'connects' to guide you.
回答配对题时，先仔细阅读所有描述再做出选择。注意“易失性”、“长期”和“连接”等关键词，它们能帮你找到正确对应关系。
4. Input and Output Devices | 输入与输出设备
Example question: State three input devices and explain the data they send to the computer.
示例题目： 说出三种输入设备，并说明它们向计算机发送何种数据。
Input devices allow users to enter data or commands into a computer system. Common examples include a keyboard (sends text characters and key codes), a mouse (sends movement coordinates and button clicks), and a microphone (sends analogue sound signals that are converted into digital data).
输入设备允许用户将数据或命令输入计算机系统。常见例子有键盘（发送文本字符和键码）、鼠标（发送移动坐标和按钮点击）以及麦克风（发送模拟声音信号，随后转换为数字数据）。
Other acceptable input devices are touchscreens, scanners, webcams and game controllers. In your answer, always link the device to the type of data it captures: for example, a barcode reader sends the numeric code encoded in a barcode.
其他可接受的输入设备包括触摸屏、扫描仪、网络摄像头和游戏手柄。答题时，始终将设备与其捕捉的数据类型联系起来：例如，条码阅读器发送条码中编码的数字代码。
Note that some devices, like a touchscreen, act as both input and output. Be precise when the question specifically asks for input devices. If a question asks for output devices, you would mention monitor (displays visual information), printer (produces hard copy) and speakers (output sound).
要注意，某些设备（如触摸屏）兼具输入和输出功能。当题目明确要求输入设备时，回答要准确。如果题目要求输出设备，则应提及显示器（显示视觉信息）、打印机（产生硬拷贝）和扬声器（输出声音）。
5. Flowchart Symbols | 流程图符号
Example question: Identify the flowchart symbol that represents a decision, and describe its role.
示例题目： 识别代表“判断”的流程图符号，并描述其作用。
A decision is represented by a diamond shape. Inside the diamond a question is written that has a 'Yes' or 'No' answer, for example 'Is x > 10?'. The flow of the algorithm then branches based on the outcome.
判断由菱形表示。菱形内部写有一个答案为“是”或“否”的问题，例如“x > 10？”。算法的流程随后根据结果分岔。
Other key symbols include the oval for start/end, the rectangle for a process or instruction, and the parallelogram for input/output. In Year 7 exams you may be asked to draw a simple flowchart from a written algorithm or to identify the correct symbol for a given step.
其他重要的符号包括：椭圆形表示开始/结束，矩形表示处理步骤或指令，平行四边形表示输入/输出。在七年级考试中，你可能需要根据书面算法绘制简单流程图，或者为给定的步骤识别正确的符号。
When drawing a flowchart, always show the direction of flow with arrows. A common mistake is to forget to label the 'Yes' and 'No' paths emerging from a decision diamond. Make sure every path leads to a clear next step or an end point.
绘制流程图时，务必用箭头标明流程方向。常见错误是忘记在判断菱形引出的路径上标注“是”与“否”。确保每条路径都导向明确的下一步或结束点。
6. Tracing Pseudocode | 跟踪伪代码
Example question: What is the output of the following pseudocode?
x ← 3
y ← x + 5
OUTPUT y
示例题目： 以下伪代码的输出是什么？
x ← 3
y ← x + 5
OUTPUT y
The arrow (←) represents assignment: the value on the right is stored into the variable on the left. First, x takes the value 3. Then y is assigned 3 + 5, so y becomes 8. The OUTPUT statement displays 8.
箭头（←）表示赋值：将右侧的值存入左侧的变量。首先，x 取得值 3。然后 y 被赋值为 3 + 5，因此 y 变为 8。OUTPUT 语句显示 8。
In more complex pseudocode, you might encounter loops and conditionals. For example, a WHILE loop repeats a block until a condition becomes false. Always perform a desk check: go through the code line by line, updating the values of variables in a table as they change.
在更复杂的伪代码中，你可能会遇到循环和条件语句。例如，WHILE 循环会重复执行一段代码直到条件变假。始终进行桌面检查：逐行执行代码，在表格中记录变量值的变化。
Practice tracing small programs to become comfortable with sequencing. Misreading the order of statements is a frequent cause of errors; remember that the lines execute from top to bottom unless a control structure alters the flow.
通过练习跟踪小程序来熟悉顺序执行。误解语句执行顺序是常见的出错原因；请记住，除非控制结构改变了流程，否则代码自上而下执行。
7. Sequencing, Selection and Iteration | 顺序、选择与迭代
Example question: Explain the difference between selection and iteration. Give an example of each from a simple game.
示例题目： 解释选择和迭代的区别。从一个简单游戏中各举一例。
paths based on a condition. In a quiz game, an IF statement might check whether the player's answer equals the correct answer: IF answer = 'London' THEN display 'Correct' ELSE display 'Try again'.
选择是指计算机根据条件在不同路径之间进行选择。在一个问答游戏中，IF 语句可能会检查玩家的答案是否等于正确答案：如果 answer = 'London'，则显示“正确”，否则显示“再试一次”。
Iteration means repeating a set of instructions. In the same game, a WHILE loop could keep asking the player for an answer until they get it right: WHILE answer ≠ 'London' DO ask for input again.
迭代是指重复执行一组指令。在同一个游戏中，WHILE 循环可以不断要求玩家输入答案，直到他们答对：WHILE answer ≠ 'London' DO 再次要求输入。
The three building blocks of structured programming are sequence, selection and iteration. Sequence is simply executing instructions in order. In exam questions, you may be given a scenario and asked to identify which structure is being used.
结构化编程的三个基本模块是顺序、选择和迭代。顺序即按顺序执行指令。考试题目中，可能会给出一个场景并让你识别使用了哪种结构。
8. Online Safety and Data Protection | 网络安全与数据保护
Example question: List three ways a strong password helps protect your online accounts.
示例题目： 列出强密码保护在线账户的三种方式。
A strong password makes it difficult for attackers to guess your credentials through brute‑force attacks. It also prevents unauthorised access if you use a different password for each service, limiting damage if one account is compromised. Finally, it reduces the risk of identity theft and unauthorised purchases.
强密码使攻击者难以通过暴力破解手段猜测你的凭证。如果你为每项服务使用不同的密码，即使一个账户被攻破，也能限制损害范围。最后，它能降低身份盗用和未经授权购物的风险。
Strong passwords typically mix uppercase and lowercase letters, numbers and symbols, and are at least 8 characters long. Avoid using personal information such as your name or date of birth. Many WJEC questions also ask about phishing: never click suspicious links or open attachments from unknown senders.
强密码通常混合大小写字母、数字和符号，长度至少 8 个字符。避免使用姓名或生日等个人信息。许多 WJEC 考题也会涉及网络钓鱼：切勿点击可疑链接，也不要打开来自未知发件人的附件。
When writing longer responses, you can refer to the Data Protection Act principles, which require that personal data be kept secure and not shared without consent. This connects online safety to legal responsibilities.
在书写较长答案时，可以提及《数据保护法》的原则，该法要求个人数据必须安全保管，未经同意不得共享。这将网络安全与法律责任联系起来。
9. Logic Gates: AND and OR | 逻辑门：与门和或门
Example question: Complete the truth table for an AND gate and give one real‑life example of its use.
示例题目： 完成与门的真值表，并举出一个生活中的实际应用例子。
| A | B | A AND B |
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
The AND gate outputs 1 only when all inputs are 1. A real‑life example is a car alarm that activates only when the doors are closed AND the key fob lock button is pressed. If either condition is false, the alarm does not set.
与门仅在所有输入都为 1 时才输出 1。一个生活实例是汽车警报器：只有当车门关闭且钥匙扣的锁定按钮被按下时，警报才被激活。如果任一条件为假，警报便不会设置。
An OR gate, by contrast, outputs 1 if at least one input is 1. This models a hallway light controlled by two switches: the light is on if switch A OR switch B is on.
相比之下，或门只要至少一个输入为 1 就输出 1。这可以模拟由两个开关控制的走廊灯：只要开关 A 或开关 B 接通，灯就亮。
In WJEC papers, you may be given a logic circuit diagram and asked to work out the output for a given set of inputs. Work from left to right, filling in the output of each gate, until you reach the final output.
在 WJEC 考卷中，你可能会看到逻辑电路图，并要求针对给定的一组输入计算出输出。从左到右处理，逐一填写每个门的输出，直至得出最终输出。
10. Sorting Algorithms: Bubble Sort | 排序算法：冒泡排序
Example question: Show the steps of a bubble sort to arrange the list [5, 1, 4, 2] in ascending order.
示例题目： 展示用冒泡排序将列表 [5, 1, 4, 2] 按升序排列的步骤。
Bubble sort works by repeatedly stepping through the list, comparing adjacent elements and swapping them if they are in the wrong order. Each full pass bubbles the largest unsorted element to its correct position at the end.
冒泡排序的工作原理是反复扫描列表，比较相邻元素，若顺序错误则交换它们。每一趟完整的扫描会将未排序部分的最大元素“冒泡”到列表末尾的正确位置。
Pass 1: 1, 5, 4, 2]. Compare 5 and 4 → swap → [1, 4, 5, 2]. Compare 5 and 2 → swap → [1, 4, 2, 5].
第一趟： 比较 5 和 1 → 交换 → [1, 5, 4, 2]。比较 5 和 4 → 交换 → [1, 4, 5, 2]。比较 5 和 2 → 交换 → [1, 4, 2, 5]。
Pass 2: ,4 (no swap) → compare 4,2 → swap → [1, 2, 4, 5]. No further swaps needed; list is sorted.
第二趟： [1, 4, 2, 5] → 比较 1 和 4（无交换） → 比较 4 和 2 → 交换 → [1, 2, 4, 5]。无需进一步交换；列表已排好序。
In the exam, showing the list after each pass is usually sufficient. You can also note that bubble sort is simple but inefficient for large lists. An optimised version stops if a pass makes no swaps, indicating the list is already sorted.
考试中，通常只需展示每趟扫描后的列表即可。还可以指出冒泡排序虽然简单，但对于大型列表效率不高。优化版本如果某趟没有发生任何交换就提前停止，表明列表已排序。
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