完形填空是英语考试中常见的一种题型，这种题被专家称为障碍性阅读，也是考生最为棘手的题型之一。它是由出题者在一篇语义连贯的文章中有目的地去掉一些词语，形成空格，要求在给出的对应的备选答案中，选出一个正确的或最佳的答案，使文章恢复完整。它既考查对语法，词汇，习语，句型，搭配等基础知识的综合运用能力，又考查对短文的阅读理解能力。

Globalwarming could cook tropical insects, with unpredictable knock-on effects, sayresearchers who warn that rising temperatures also______(51) tropical frogs,lizards (蜥蜴).

Temperaturesare ______ (52) to increase much faster in temperate(温和的) andpolar(极地的)regions than in the tropics. But no-one had looked at how warming would affectinsects and other cold-blooded animals ______ (53) had evolved in tropicalregions with little temperature variation.

CurtisDeutsch at the University of California at Los Angeles and colleagues analyseddata ______ (54) insect survival and reproduction for 38 species in differentecosystems(生态系统), andthen estimated how these values would ______ (55) with predictions of climatechange for the 21st century.

Theteam found that the reproductive ______ (56) of tropical insects tends to peakvery close to the temperatures where they normally live, but______ (57) sharplyat higher temperatures. This means that cranking up (提高)theheat only a small amount can exert a heavy toll, leaving insects unable toreproduce ______ (58) enough to keep up their numbers.

Temperaturetolerance

Temperateinsects reproduce well over a broader range, and do not live as ______ (59) totheir thermal(热的)limit, so they can reproduce successfully when their climate warms more than inthe tropics.

“Tropicalinsects do very well in a narrow band of temperatures, but move them above that______ (60) and they die,” says team member Josh Tewksbury of the University ofWashington in Seattle.

Theheart of the ______ (61) is temperature tolerance. emperate-zone insects haveevolved to survive the much broader temperature swings of seasonal climates,than have their tropical relatives.

The______ (62) appears worse for animals that live in hot stable climate of thelower levels of tropical forests. Lizards in clear areas can find shade to cooldown, but those living in the forest are already in the ______ (63), andthere's not much they can do to get cooler, Deutsch says.

Too fewtropical insects have been studied so far to ______ (64) if any particulargroup will be particularly hard-hit, says Tewksbury. Insects play important______ (65) in forest ecology(生态学), including pollination, and eatingdetritus to recycle carbon.

Theteam are now starting to evaluate how temperature affects ecologicalinteractions of insects with other species, including crops such as Africancorn.

参考答案：

51 threaten 52 expected 53 that 54 on 55 change

56 rate 57 drops 58 sucessfully 59 close 60 range

61 problem 62: effect 63 shade 64 tell 65 roles