Dealing with grammatical errors

Students in your class make the following errors.

Figure out a) what is wrong and b) how you would explain it to your students.

1. I know him for five years.
2. I have a lot of trouble with John at the moment.
3. He didn't came.
4. I really must stop to smoke.
5. You are American, isn't it?
6. When I arrived, they were waiting for half an hour.
7. I can to swim.
8. This weekend, I went to shopping with my friend.
9. The whiskey is a stronger drink than the sherry.
10. I live there since ten years.
11. Do you know where is my country?
12. I need two breads.
13. They live in the house white.
14. Do she goes to the play?
15. They were waiting the bus.
16. We went to get some furnitures for our house.
17. He was eat his dinner when I came.
18. Tokyo is very safety city.
19. I am boring in this class.