Ответ:
1.There is no need to repeat the same thing.I just can't do what you want.
2.I have to take the early train myself or I'll be late for my first class.
3.Let's not argue about it now.We must first solve the first question.
4.She realized that she would have to talk to him about the matter.
5.Since you are here we can ask you a few questions?
6.He was supposed to give the money to the Secretary but I'm not sure he was able to do it.
7.In this Sunny weather, he can not do without sunglasses.
8.You may not eat the soup but the second thing you should try.
9.You will not be able to discuss this book until you have finished reading it.
10.Can you help me with my things?
11.Can't you see that she needs to work?
12.How can you force him to do something that is against his principles?