旧托福听力part C【荐】.pdf

大家论坛托福版块 44. ( A) How insects breed in extreme desert temperature. (B) Different types of beetles. ( C) Plants that survive in arid regions. How beetles can defeat a plant’s defense system.. 45. (A) Its resin isn’t poisonous. (B) It can shoot its resin a great distance. ( C ) Its leaves have no veins. (D) It doesn’t need much water to grow well. 46. (A) By severing the veins that carry the poison. (B) By eating only the stem of the plant. ( C) By changing the plant’s chemistry. (D) By eating only at night. Questions 44 through 46 Listen to a talk in a biology class. This morning I ______________a recent scientific discovery dealing_______________________________. This is about a desert shrub ___________________________six feet. Do you think it would be safe from all attacks by insects? But a recent study has found one insect, a beetle that can chew its way past the plant’s defense system by __________________________. This vein cutting is just one method the beetles used to prepare a safe meal. ________is by cutting a path all the way across the leave to hold the flow of chemicals. Then they simply eat between the veins of poison._________, scientists who studied insect adaptation to plant defenses have focused on chemical responses. That is, how the insects can neutralize or alter the poisonous substances plants produce._____________ this chewing strategy is that the beetle is actually exhibiting a behavioral response to the plant’s defenses rather than the more common chemical response. It is only after a beetle’s survived several encounters with the plant’s resin that it learns how to avoid the poison: by chewing through the resin tra