We must do everything we can _________ our earth clearer and safer.

--- I don’t mind telling you what I know.
--- You _______. I’m not asking you for it.

We have so many kinds of guitars for you ________.

—We can use QQ to talk with each other online.
—Really? Could you show me ______it?

There is no bridge or boat. It’s difficult for people_____the river
A. cross    B．to cross    C. crossing

If you are tired, please stop    a rest.

Thank you ____ me with my homework.

– Which is the best way ____ to school?
-- By bus.

It takes me half an hour ________ my homework.

He decided ______ on Tuesday.
A.leave     B.to leave   C.leaves