I haven’t received your letter. It might _______ delivered to the wrong address.
A. be                      B. to be                       C. have been                D. has been

We _______ leave yet. We’ve got plenty of time to get to the station.
A. aren’t necessary to                     B. mightn’t                  C. don’t have to              D. couldn’t

She wishes she would become a famous singer, _______?
A. doesn’t she B. may she C. does she D. may not she

If an animal didn’t attack me first, I’d never kill it, _______?
A. may I                   B. had I                  C. would I               D. will I

Làm sao để tách

   a)một hỗn hợp muối, sỏi và thóc 

 b) 1 hỗn hợp gồm đường, đá xây dựng và gạo??