________ environmental damage is done, it takes many years for the ecosystem to recover．

A．Once

B．Even if

C．While

D．If only

It is required that the students ________ mobile phones in their school, so seldom ________ them using one．

A．mustn't use; will you see

B．should not use; you will see

C．not use; you will see

D．not use; will you see

Undoubtedly speaking, Jobs' digital products are of great benefit to ________ applies them at work．

A．what

B．whatever

C．who

D．whoever

Could you ________ this 20-dollar bill?I need some change to make a phone call．

A．divide

B．tear

C．break

D．cut

More often than not, young readers find the novels of Dickens far more exciting than ________ of Thackeray．

A．ones

B．them

C．these

D．those

A local publicity official said a trampling accident happened at a private school in Xiangtan city, Hunan Province, ________ eight dead and twenty－six ________．

A．leave; injured

B．left; injured

C．leaving; injuring

D．leaving; injured

Only when ________ hard ________ make your dream come true．

A．do you work; you can

B．you work; you can

C．do you work; can you

D．you work; can you

Most of us still wonder ________ it is ________ makes those honest peasant workers, without being paid at all, resign themselves to the bosses．

A．what; that

B．/; what

C．that; what

D．/; that

Angela and Ajani will pick up the marriage ________ after they meet online several thimes, which is not sensible．

A．acquisition

B．identification

C．certificate

D．qualification

Barack Obama delivered a speech to 500 local youths during his visit to China, many of ________ were from Fudan University and Tongji University．

A．them

B．whom

C．which

D．those