1选择题
Look at the ruler. It is 15 ________ long.
- A. millimetres
- B. centimetres
- C. metres
- D. kilometres
答案：B
解析：本题考查长度单位的选择。根据生活常识，尺子的长度通常用厘米(cm)表示。15毫米太短，15米和15千米又太长。易错点是混淆不同长度单位的实际大小。
2选择题
There are 24 hours in a day. What time is it when it's '3 o'clock in the afternoon'?
- A. 3 a.m.
- B. 3 p.m.
- C. 15 o'clock
- D. 13 o'clock
答案：C
解析：本题考查24时计时法。下午3时，用24时计时法表示是15时。选项A和B是12时计时法，D是下午1时。易错点是混淆12时和24时计时法的转换。
3选择题
What is the perimeter of a square with a side length of 5 centimetres?
- A. 10 cm
- B. 15 cm
- C. 20 cm
- D. 25 cm
答案：C
解析：本题考查正方形周长计算。正方形周长 = 边长 × 4，所以 5 cm × 4 = 20 cm。易错点是误用长方形周长公式（长+宽）×2，或计算错误。
4填空题
My brother is 12 years old. I am 4 years old. My brother's age is ________ times my age.
答案：three
解析：本题考查“倍的认识”。哥哥12岁，我4岁，12 ÷ 4 = 3，所以哥哥的年龄是我的3倍。注意“times”表示倍数，答案用英文单词。
5填空题
A box weighs 2 tons. A car weighs 1 ton. The box is ________ times as heavy as the car.
答案：two
解析：本题考查“倍的认识”和质量单位吨(ton)。箱子重2吨，汽车重1吨，2 ÷ 1 = 2，所以箱子是汽车重量的2倍。
6填空题
A chocolate bar is divided into 8 equal parts. If I eat 3 parts, I have eaten ________ of the chocolate bar.
答案：three eighths
解析：本题考查分数的初步认识。一个整体平均分成8份，取其中3份，用分数表示是八分之三。易错点是分子分母位置颠倒，或读写错误。
7解答题
Tom has 3 boxes of crayons. Each box has 18 crayons. How many crayons does Tom have in total? (Please write a number sentence and the answer.)
答案：Number sentence: 3 × 18 = 54. Tom has 54 crayons in total.
解析：本题考查多位数乘一位数（进位）。3 × 18，可以拆分为 3 × 10 = 30, 3 × 8 = 24, 30 + 24 = 54。易错点是进位计算错误，例如 3 × 8 = 24，忘记加进位。
8解答题
The school library is 2 kilometres from the classroom. The playground is 500 metres from the classroom. How much farther is the library than the playground? (Please show your calculation steps.)
答案：Step 1: Convert units to make them the same. 2 kilometres = 2000 metres.
Step 2: Calculate the difference. 2000 metres - 500 metres = 1500 metres.
Answer: The library is 1500 metres farther than the playground.
解析：本题综合考查长度单位换算（千米和米）和万以内的减法。易错点是单位未统一就直接计算（如用2-500），导致结果错误。必须先统一单位（2千米=2000米）再相减。