I think you need some outdoor exercise．Plenty of fresh air will ________ good health．

A．contribute to

B．devote to

C．apply to

D．adjust to

________ you may have, you should gather your courage to face a challeage．

A．However a serious problem

B．What a serious problem

C．However serious a problem

D．What serious a problem

The school rules state that no child shall be allowed out of the school during the day, ________ accompanied by an adult．

A．once

B．when

C．if

D．unless

Many volunteers have been ________ to give more help to the local people since the earthquake happened．

A．eager

B．anxious

C．worried

D．curious

It was said by Plato ________ he would never stop practicing and teaching the truth while he had life and strength．

A．how

B．whether

C．that

D．/

He ________ in debt for a long time．How to support his family is a big problem．

A．was

B．is

C．has been

D．had been

No one is sure ________ global warming can be solved in one hundred years．

A．whether

B．why

C．that

D．where

Many scientists believe that the universe began with an enormous explosion called the “Big Bang”, ________ happened about 13.7 billion years ago．

A．that

B．which

C．when

D．what

She is a nice girl, with a gift ________ developing friendship with others．

A．in

B．on

C．for

D．about

The couple had a(an) ________ quarrel because of the housework and John rushed out angrily．

A．violent

B．harmful

C．impressive

D．unbelievable