（ ） has already been pointed out before, English grammar is not a set of dead rules.

The government cannot operate effectively （ ） it is free from such interference.

I recognized John （ ） he entered the room.

The price of fish is （ ） during the Spring Festival.

I can’t find my keys! Can you help me （ ） them?

The defense computers calculate way to （ ） the enemy missiles.

_____, the professor is still trying to learn a new language.

I stayed up all night _____ to find a new solution to the problem.

It was not known （ ） he had said during the interview.

Mass production has made （ ） the goods and services we want at a lower price.

My children are looking forward to （ ） a trip to Paris.

She insisted that the seats in the theater （ ） in advance to insure a better view．