You ___ the door before leaving the house. Why didn't you ...

★ Modals with Perfect Infinitive

You ___ the door before leaving the house. Why didn’t you do that?

A. should have locked

B. must have locked

C. might have locked

D. may have locked

Preview next quiz:

I’m not sure but our neighbours ___ some noises when our car was stolen.

A. should have heard

B. can’t have heard

C. must have heard

D. might have heard