—Is Tom still in New York or already back at home? —I’m not sure _________. I’ll call to make sure.
My father usually drives to work ______ taking the bus.
.---Do you know if Jim______ to play basketball with us? ---I think he will come if he ______ free tomorrow.
The art club is for members only. You can’t go in _____ you are a member.
Our teacher asks us to remember that _______ careful we are, _______ mistakes we will make.
My aunt said that she ________ to Guangzhou. A has never gone B.had never gone C.has never been D. had never been