49. Many scientists carried out _______ healthy food.

　　　 A. a research for　 B. a research into　 C. research in　 D. researching into

48. Mr Smith gave us _______ on bow _______ the computer.

　　　 A. an advice, to use　　　　　　　　 B. some advice, to use

　　　 C. advices, using　　　　　　　　　 D. pieces of advices, using

47. Now let's ______ to show how deep ploughing works.

　　　 A. take it as an example B. take it for an example C. give example D. for example

46. Please ______my regards to your parents.

　　　 A. pass by　　　　 B. pass on　　　　 C. pass out　 D. pass away

45. Not the students but the teacher _______ the results of the exam.

　 　　A. are anxious to know　　　　　　　 B. is looking forward to know

　　　 C. is anxious to know　　　　　　　 D. are looking forward to knowing

44. _______ the improvement of living conditions, people's eating habits are changing _____ these years.

　　　 A. For, during　　 B. With, over　　 C. As, in　　 D. Because, over

43. It was _______ the Sep. 11th Attack that the American people ______ the danger of terrorism.

　　　 A. until, didn't realize　　　　　　 B. not until, realized

　　　 C. not until, did realize　　　　　 D. until, realized

42. It was only when I reread this poems recently _____ I began to appreciate their beauty.

　　　 A. until　　　　 　B. that　　　　　 C. then　　　 D. so

41. It was m until 1920 ________ regular radio broadcasts began.

　　　 A. while　　　　　 B. which　　　　 C. that　　　 D. since

40. It is the ability to do the job ___ matters not where you come from or what

　　　 you are.

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