In hot summer, milk quickly turns sour(酸的)       it is refrigerated.

    A. while           B. if              C. unless         D. until

---Don’t you think the new job is a real challenge for Jack?　

---Well, 　　 difficulties he meets, I believe he will never lose heart.

　 A. whatever　 　　 B. however　　 C. whichever　　　 D. whenever

      too much for his intelligence, Harry often overlooks the importance of effort.

    A. Praised           B. Having praised      C. praising    D. Being praised

She often shares her deepest thoughts and fears with friends through QQ, as if they______   chatting in her living room. 

   A.      had been       B. are             C. were             D. has been

---John, why are you so upset?

---I??? 　　 my cell phone all morning but it is nowhere to be found.

A. am looking for B. have been looking for 　

C. have looked for　　　　 D. had looked for

The number of people present at the concert was _________ than expected .So there were many tickets left .

A. many more   B. much more   C. much larger   D. much smaller 

 We are invited to a party ________ in our club next Friday.

  A. to be held     B. held            C. being held       D. holding

Talking with Premier Wen face to face was an unforgettable moment, ________ the low-income families always treasure.

A. it                      B. that                   C. what          D. one

Mo Yan became the first Chinese Nobel Prize winner in Literature, _______left school to make a living at the age of 12.

  A. as            B. which          C. who        D. that

 It is said that walking is one of the best ways for a person to ________ healthy.

A. reserve              B. preserve              C. stay                 D. obtain