4 . 单句改错，每个句子中有且只有一个错误
1. People don’t have enough exercise are more likely to have heart attacks.
2. As is known to all, 70% of the air you breathe in every day are nitrogen (氮气).
3. With the help of the teachers, most of the students have made great progresses.
4. Though knew the truth, the witness of the case remained silent for some reason.
5. My grandma used to tell me that a losing opportunity never returns.
6. Can you help Jane out? She can’t make herself understand in class.
7. When it comes to find excuses, she is an expert with whom no one can compare.
8. Xi’an, known as Chang’an then, has become the world’s largest city by the Tang Dynasty.
9. Unfortunate, the car accident claimed two lives and left four injured.
10. Riders are often scared for the first time they get on a horse.

8 . 增加：在缺词处加一个漏字符号(∧)，并在其下面写出该加的词。
删除：把多余的词用斜线(＼)划掉。
修改：在错的词下划一横线，并在该词下面写出修改后的词。
1. Seeing her missing child coming back, the woman couldn’t help but to cry.
2. The girl to who I am speaking is my closest friend.
3. I will never forget the day when I met you the first time.
4. That surprised us most was that the old man hadn’t been outdoors for 20 years.
5. By the time he arrived at the theater, the movie begun.