改正如下：
1.A man was sitting by the road, eating a sandwich. When a policeman appeared,
2.the man got up very quickly and ran along the road. The policeman
3.saw and ran after him. After a few minutes, the policeman 4.caught him. "Where are you going?"
5.asked the policeman."I'm sure you are a thief.Why did you run like that
7.when you saw me?"
"No,I'm not a thief.I'm too
8.fat,you see.I went to see the doctor
9.and I was told that I must lose some weight.He told me to run very fast
10.immediately after eatting."