Grammar Questions

1. 'What’s happen to you?’ she asked (in/ with) surprise. (Why the correct answer should be in?)
2. We are sure (about/ of) his intention. (Why the correct answer should be of?)
3. The helicopter is flying (on/ over) the sea to Macau. (Why the correct answer should be over?)
4. It was careless of you to leave your umbrella (on/ in) the bus. (Why the correct answer should be on?)
5. The village is beyond the mountain. You can see it (at/ from) the top. (Why the correct answer should be from?)
6. You have an appointment with Mr Lau.
   You: I’m Robert Choi. Mr Lau is expecting me.
   Receptionist: Yes, I know. Mr Lau has asked me to show you in when you come. If (you’d follow/ you follow) me, I’ll take you to his office.
   You: Thanks.
   (Why the answer should be the former?)
7. Why we say ‘She can’t have been 18 last year’ instead of saying ‘She couldn’t have been 18 last year’ or ‘she couldn’t be 18 last year’?