4. We have to stay at home because the bad weather.

5. It was not until darkness when I began to do my homework.

6. Because Tom works hard, so the teacher often praises him.

7. The factory where I visited last week is not far from here.

8. Please contact me if you have any difficulty find the watch.

9. A good robot needs checking every six month.

10. What the boy didn't take medicine made his mother angry.

答案：

1. The play is based in a true story. on

2. The number of boys in our class are 50. is

3. He looked puzzling so I repeated the question. puzzled

4. We have to stay at home because ∧the bad weather. of

5. It was not until darkness when I began to do my homework. that

6. Because Tom works hard, so the teacher often praises him. so

7. The factory where I visited last week is not far from here. that 或which；或把where删掉

8. Please contact me if you have any difficulty find the watch. finding

9. A good robot needs checking every six month. months

70. What the boy didn't take medicine made his mother angry. That

【分析】

本文是改错题。改错对考生的要求较高，主要考查学生对语言知识综合运用能力，检测考生发现、判断、纠正文章错误的能力，进而考查学生的词法、句法及行文逻辑等方面的水平。在做题时要注意具体语境中的时态及语态，以及固定搭配的用法。

【1题详解】

考查固定搭配。句意：这出戏是根据真实故事改编的。 be based on....为固定搭配，意为"以....为基础" ，所以把in 改为 on。

【2题详解】

考查主谓一致。句意：我们班男生数是50。本句的主语是the number,意为"....的数量"，作主语，谓语动词要用单数，故把are 改为 is。

【3题详解】

考查形容词。句意：他看上去很困惑，于是我重复了一遍这个问题。Puzzling意为"令人困惑的"，一般用于修饰物。而 puzzled意为"困惑的"，一般用于修饰人或人的表情。分析句子可知，本句中是修饰主语he,所以要用puzzled。故把 puzzling改为 puzzled 。

【4题详解】

考查固定用法。句意：因为天气不好，我们只好呆在家里。Because是连词，后面跟一个从句，而because of...为介词短语，后面跟名词或名词短语。分析句子可知，本句中的the bad weather.是名词短语，不是句子，所以要用because of。因此在 because加上 of。