find the mistakes in the following sentences
1.she had to stop to laugh because the teacher came in.
2.we live in a big room which windows face south.
3.as we all know,taking exercise are good for our health.
4.why not to go out to have a walk instead?
5.wcording to our research,china will be one of most important countries in the world.
6.My teacher gave me a good advice.
7He returned home in the afternoon of his birthday.
8.we look forward to hear from you.
9.unless he works more harder,he will certainly fail.
10.The Smiths did his best to make me feel comfortable.
11His father is a engineer,who works in a factory in North China.
12We are busy to prepare for the examination.
13I don't think the ice is enough hard to skate on.
14The question is too easy.Even a three-year-old children can do it.
15why not going by bus instead?
16My father has bought the TV set for about ten years.
17The factory where you are going to visit tomorrow is not far.
18The house was hot in the summer and cold in winter.
19Rose leaved Hangzhou for Beijing the day before yesterday.
20How funny-looking clothes the old man is wearing.
21Mrs.Green with his two students are sitting in her garden.
22Some of the students in my class don't well in English.
23Each of you are responsible for the accident.
24The kite flew so highly that I could hardly see it.
25He accepted his mother's praise after he was elected chairman of the organization.
26We must do as much as we can help the poor students.
27Every means have been tried but without any result.
28China food contains too many oil.
29You'd better to study hard if you want to pass the exam.
30Tom.as well as hrother and sister,go to park every day.