46. Mike’s success is _________ his hard work and his ability to formulate plans which will get work done efficiently.

　　A. owe to B. as to

　　C. due to D. according to

　　47. Scientist now have some surprising answers about whether brain power ________ as we get older.

　　A. deduces B. descends

　　C. collapses D. declines

　　48. Who is going to ________ the job of Dr. Johnson has not been decided yet.

　　A. take over B. drive on

　　C. sort out D. keep up

　　49. This project can _______ the region so that crops there may suffer no more drought.

　　A. irritate B. irrigate

　　C. isolate D. illuminate

　　50. The police stopped me the other day as I was driving home, because I was exceeding the speed _________ .

　　A. limit B. limitation

　　C. minimum D. maximum

　　51. There were some ________ flowers on the table, which were made of silk.

　　A. fresh B. false

　　C. artificial D. natural

　　52. Citizens in this country are now enjoying better dental health, as shown by the declining incidence of tooth __________ .

　　A. care B. decay

　　C. growth D. reflection

　　53. People who are _________ to wool shouldn’t wear woolen clothing.

　　A. sensitive B. initiative

　　C. integrative D. repetitive

　　54. In order to help the listeners get a better understanding of the new conception, the lecturer _________ it with many examples.

　　A. practiced B. dominated

　　C. estimated D. explained

　　55. The labor leaders realize they will have to make some concessions in their demands in order to ________ an agreement.

　　A. meet B. invite

　　C. reach D. move