It is important for us _____ our English.

_____did it _____the conductor to check the tickets this morning?-Half an hour.[ ]

There is still a copy of the book in the library. Will you go and borrow ?—No, I’d rather buy in the bookstore.

Dad, must we wait until the light becomes green? — Yes, I’m afraid we ______. That’s the traffic rule.

What a delicious joke! This sentence means _____.