55. ---- How long do you think it is______ he arrived here?

---- No more than half a year, I believe.

A. when B. that C. before D. since

54. Pandas would die ______ if people were allowed to hunt ______ they wished.

A. out; as many as B. away; more than

C. off; as much as D. out; less than

53. This is the only painting in this style ____________ we have.

A. which B. that C. in which D. in that

52. ___________ from space, the earth looks like a blue ball.

A. To see B. Seeing C. See D. Seen

51. I suggested the meeting ______ at the manager’s office.

A. hold B. be held C. is held D. is to be held

50. Today, we _____ work as hard as people did in the past.

A. mustn’t B. can’t C. shouldn’t D. don’t have to