-----Did Mary come to the party?
---I don’t know．She _____while I was out．

--Shall Mary come and play computer games?

--No,__________ she has finished her homework.

A. when         B. if               C. unless    D. once

--Shall Mary come and play computer games?

--No,__________ she has finished her homework.

--- Has Mary come back yet?

 --- Yes. She has got many books from her elder schoolmates, and the number  ___ 1000.

A. adds up          B. adds up to       C. add to       D. add up to

—Did Mary come to the party?

—I don’t know.She______while I was out.

A.may have come                       B.must have come

C.might come                            D.could come