四、阅读理解（总计20小题，每小题2分）
第一节、根据短文内容，选出最佳选项（总计15小题，每小题2分）
Can trees talk? Yes—but not in words. Scientists have reasons to believe that trees do communicate with each other. Not long ago, researchers learned some surprising things. First a willow tree(柳树) attacked in the woods by caterpillars(毛毛虫) changed the chemistry of its leaves and made them taste so terrible that the caterpillars got tired of the leaves and stopped eating       them. The even more astonishing, the tree sent out a special vapour — a signal causing its neighbours to change the chemistry of their own leaves and make them less tasty.
Communication, of course, doesn’t need to be always in words. We can talk to each other by smiling, raising our shoulders and moving our hands. We know that birds and animals use a whole vocabulary of songs, sounds, and movements. Bees dance their signals, flying in certain patterns that tell other bees where to find nectar(花蜜) for honey. So why shouldn’t trees have ways of sending messages?
56. From the passage we know that caterpillars _______.
A. like willow trees                       B. enjoy eating fallen leaves
C. can talk to other caterpillars        D. can send out a special vapour
57. Caterpillars will stop eating willow tree leaves which _______.
A. have a chemical change and become tasteless  B. have a pleasant taste
C. are being attacked                        D. are communicating
58. According to the passage, bees communicate with each other by _______.
A. talking                                             B. making unusual sounds    
C. singing songs                              D. flying certain patterns