Unit 5 Meeting your ancestors课时作业

Using language

第一节.阅读七选五(共5小题；每小题2分，满分10分)

　　根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

　　Each year, many animal species die out. They join the countless species that have gone extinct (灭绝的) over the course of the earth's history and many people believe they disappear forever.__1__

　　Now some scientists are focusing on the ability to bring back extinct species. This doesn't mean the plot of Jurassic Park is going to become a reality. The researchers need DNA to clone a species.__2__ Dinosaurs have been gone too long for any of their DNA to remain in fossils (化石)．

　　But there's a very real chance that we will be able to bring back more recently extinct species. __3__ In 2003, a team of Spanish and French scientists recreated the Pyrenean ibex, which had gone extinct three years earlier. The new animal didn't survive long, but scientific advances could improve the success rate. In January, Australian scientists announced that they were on their way to bringing back the gastric brooding frog.

　　That we can bring species back doesn't mean that we should do that. There may be much benefit of reviving (使复生) a species, but there's no way to know how it will turn out. __4__ Or might it crowd out existing species? Environmentalists worry that our ability to bring species back might cut down support for the hard work of traditional conservation.

　　__5__ If we can correct our mistake, why not use the chance to do that? As Stewart Brand, a businessman and environmentalist, recently said，"Humans have made a huge hole in nature. We have the ability now to repair some of that damage."

　　A．DNA is the chemical that carries the structure of a living thing.

　　B．In addition, most people think that the extinction of some animals is really humans' mistake.

　　C．However, some people argue that the extinction of some animals is really our mistake.

　　D．This could even include Ice Age animals like the woolly mammoth.

　　E．However, you might need to redefine (重新定义) "forever"．

　　F．This could even be true to dinosaurs that were extinct long ago.

　　G．For example, would a passenger pigeon fit into its old habitat (栖息地)?

　　答案：1～5　EADGC

第二节.完形填空(共20小题；每小题1.5分，满分30分)

阅读下面短文，从短文后各题所给的A、B、C和D四个选项中，选出可以填入空白处