188. Jack almost fell off the cliff, but managed to _____ until help came.

　A. keep on B. catch on C. count on D. hang on

187. The storm sweeping over this area now is sure to cause _____ of vegetables in the coming days.

　A. rarity B. scarcity C. invalidity D. variety

186. Don't _____ the news to the public until we give you the go-ahead (许可，准许).

　A. release B. discard C. relieve D. retain

185. If you _____ your demand, then maybe you will have more chance of getting what you want.

　A. conduct B. dismiss C. grant D. moderate

184. His _____of the aeroplane was correct in every detail and could really fly.

　A. shape B. pattern C. design D. model

183. The open university was started in order to help those who _____ having a university education when they were young.

　A. stopped B. failed C. missed D. ceased

182. The magician picked several persons from the audience and asked them to help him with the performance.

　A. by accident B. on occasion C. at random D. on an average

181. He has left his book here on _____, so that you can read it.

　A. purpose B. intention C. aim D. meaning

180. I remember her face but I cannot _____ where I met her.

　A. recall B. remind C. remember D. remark

179. The climbers _____ their ambition by reaching the summit of the mountain.

　A. obtained B. sustained C. maintained D. realized