The present question is ____ many students consider it impossible ____ is really possible if effort is made.

The question that puzzled them is ____ they can get rid of the air pollution in the area.

The limits of a person’s intelligence, generally speaking, are fixed at birth, but ________he reaches these limits will depend on his environment.

Only after Mary read her essay the second time            the spelling mistake.

He is only too ready to help others, seldom, ____, refusing them when they turn to him.

      your pets inside as much as you can when the weather is bad.

Jim told us all that _______ he said so at the meeting was right.

______ for the boy to talk with his mouth full!

_______ is known to us all is that the theme of Shanghai World Expo is “Better City, Better Life”.

_______ his return from America, he got down to his research.