I used to smoke _____ but I gave it up 3 years ago.

The most important is not_____ you do, but_____ you do it.

We could see the stars （ ） well from the top of the mountain.

（ ） you decide to take up, you should try to make it a success.

I think it’s high time we _____ strict measures to stop pollution.

Three of us will go there, and the rest （ ） to stay here.

（ ） some mammals came to live in the sea is now known.

No one should blind himself （ ） the well-known fact.

（ ） we can succeed or not depends on how well we cooperate with others．

Many young people find it harder to appreciate_____music than pop music.

Herman’s success is （ ） his hard work and his academic ability.

Such a skilled tennis player knows how to take_____of his opponent’s (对手) chief weakness.