It must be kept in mind that      lifelong study can you survive in the highly competitive society.

A. only when      B. until then       C. only through         D. until when

______ you eat the correct foods ______ be able to keep fit and stay healthy.

       A. Only if; will you                                     B. Only if; you will  

       C. Unless; will you                             D. Unless; you will

The computer was used in teaching. As a result, not only _____, but students became more interested in the lessons.

A. saved was teachers’ energy                   B. was teachers’ energy saved

C. teachers’ energy was saved                    D. was saved teachers’ energy

       Only when you leave your parents for college education _______ how much you love them.

A. do you realize    B. you realize        C. you will realize  D. will you realize

Such great achievements ____ so far that many friends abroad can hardly believe that.

A. has China made                             B. China has made 

C. does China make                            D. are made in China

________it in the flesh, I would never have known the drought in southwest China is so serious and people are suffering so much.

       A．Had I not seen         B．If I did not see

       C．Should I not see             D．Were I not seen

So serious        that all the persons on board were killed.

  A. was the accident  B. did the accident    C. the accident was   D. the accident did

Only lately        about the dark secrets behind the seemingly-happy marriage of the golf star Tiger Woods.

       A．the public have known    B．were the public known

       C．have the public known    D．the public knew

So difficult _____ it to adjust to an English-speaking environment that he determined to learn English hard.

A. he has felt         B. has he felt         C. he did feel         D. did he feel

Only by communicating with each other more frequently ________ clear away the misunderstandings and solve the conflict.