He promised ______ his daughter a new bicycle as a birthday present.

A. buy

B. to buy 

C. to buying 

D. buying 

Unless you _______ all of my questions, I can’t do anything to help you.

A. answered 

B. answer 

C. don’t answer 

D. are answering

Because of electronic publishing, ______ will disappear in the next 25 years.

A. a book 

B. book 

C. the books 

D. books