Who can tell me where is there a mistake? Thank you so much.

1. If it rains tomorrow, what will you do?
2. I would give it to medicine research, if I got a lot of money.
3. This old man had 2 millions dollars, but he gave it to charities.
4. He should eat lots of fruits and vegetables and drinks lots of water
5. He didn't know whether he should  bring a present when invited.
6. If we had left earlier this morning, we wouldn’t miss the bus
7. If you don’t know anyone, you can talk with Tom.
8. If I were you, I would talk to someone who looked  friendly.
9. If I were you, I would take a long walk before went to bed.
10. I can’t sleep in the night before take a big exam.
11. I have no gift, what if anybody else brings a gift.
12. Confident people dare to speak in public.
13. Both of them are going to concert this evening.
14. I really need it because  I have a math test.
15. In my dream, I was swimming in an papers of ocean  .
16. I am really anxious, because I can’t find out my backpack.
17. It is happened Strange things in our neighborhood.
18. Have you ever been to any other country?
19. Social situations doesn't bother you in the slightest.
20. Sometime you might annoying  because you’re so confident.