Complete these sentences with tag questions

II.         Complete these sentences with tag questions.
7.         There are many problems, _______?
8.         You have never read scientific books, _______?
9.         He has studied English for ten years, _______?
10.     I’m old enough to join the club, _______?
11.      They think he is intelligent, _______?
12.      Don’t touch that button, _______?
13.      She hardly drinks coffee, _______?
14.      Let’s go out for dinner tonight, _______?
15.      It never works very well, _______?
16.      Somebody wanted to open the window, _______?