We need clean air and water. So we__________ protect the environmen.

A.must B.can C.may

We can make a fire__________the room warm so that we can chat for a while.

A.to keep B.keeping C.keep

--Ruby,__________the steps when you wear shoes with high heels.

--Thanks,I will.

A.minding B.mind C.to mind

-- Would you like to buy this watch?

--I'm afraid I cant afford it I want to buy a(n),__________one.

A.expensive B.cheaper C.cheap

--Lisa, have you ever visited Mountain Tai?

--Yes, I__________in Mountain Tai for three days and enjoyed myself there.

A.stay B.stayed C.have stayed

__________it was very cold outside, many people went to the park to take exercise.

A.Until B.Though C.If

I think the restaurant is great because the customers here__________the best service in town.

A.are given B.give C.have given

--I hope you can__________the problems and complete the work on time.

--I will.

A.get off B.get over C.get up

Mary is a pretty girl in our class__________always likes to help others.

A.who B.whose C.whom

__________exciting news it is!

A.What B.What an C.How