Evidence gained from observation and experiment is often used to _______ a scientific theory. 

A．concern          B．confirm           C．consult           D．combine

He left home without saying a word, and _______ worries many people and is to be found out.                                

A．where he has gone                      B．where did he go

C．which place has he gone                  D．where has he gone

The local government announced that only when the fire was under control ________ to return to their homes.

A．the residents would be allowed            B．had the residents been allowed

C．would the residents be allowed             D．the residents had been allowed

Mary _______ her mother with the housework, but she didn’t.  

A．must have helped                       B．ought to have helped

C．must help                             D．should help

The transformation of our city will make _______ for people here to have a comfortable environment.                     

A．it possible         B．no possibility       C．impossible         D．there was possibility

It is said that the temperature is unusual mainly _______ global warming caused by human activities.

A．in spite of         B．by means of        C．in case of          D．on account of

Two people were killed in the serious car _______ the other day.  

A．strike            B．break             C．crash             D．incident

 In order to be _______ for Christmas, all these gifts must be mailed immediately.

A．in time           B．at one time        C．at a time          D．in no time

— Why does she always ask you for help?            

— There is no one else _______, is there?

A．who to turn to                          B．for her to turn

C．for whom to turn                        D．she can turn to