C. Choose the words or expressions to complete the passage (选择最恰当的单词或词语完成短文)

We have always been warned of the dangers of forest fires. They cause _____ 15 _____ to a forest. They kill many plants and animals in an eco-system, which is a group of living things and their environment. But have you ever heard of a forest fire that can be _____16_____ for a forest? People start some of the fires with a special reason to actually do good to the eco-system.

In fact, fires are a natural part of any eco-system. Without fires, the oldest and largest trees would stop sunlight from reaching the forest floor. Fires can _____17_____ some of these old trees. When the trees die, they provide something good for the earth. New trees can grow strong and healthy in their place.

Some trees even need fires to grow. These trees hold their seeds (种子) inside. Heat from a fire allows the coat of the seeds to open up. Then the seeds fall to the ground and have the _____18____ to grow/

Scientist, who know about nature’s needs, start some of these fires, called controlled burns. A fire is started and kept under control. This way, the fire does not spread out of the area or _____19_____ a after forest fires, they can go hungry _____20_____ their food has been damaged in the fire. Small, controlled fires mean than animals will not have to move far to find food. After some time, small plants begin to grow. Animals return soon after the plants return. This _____21_____ makes an eco-system.

So the next time you hear about a forest fire, think about the good as well as the bad. It may take a new eco-system a while to return, but it will likely come back stronger and healthier than ever.

15. A) illness B) difficulty C) damage D) flood

16. A) helpful B) powerful C) harmful D) awful

17. A) take the place of B) get ready for C) be bad for D) get rid of

18. A) time B) water C) chance D) skill

19. A) discover B) cover C) but D) waste

20. A) because B) although C) but D) so

21. A) almost B) again C) never D) even

【主旨大意】

文章指出森林火灾并不像人们想象的那样一无是处，有时候，可控范围内的火灾不仅无害而且还具有积极意义。比如，可控制的火灾可以使森林里的老树、死树烧掉，使阳光能够照射到地面；火灾烧掉了一些种子外层包裹的厚厚的皮，并让种子有机会得以在地面上生根发芽。

15. C 【解析】该句意为“森林火灾会对森林引起毁坏”，damage名词，意为“毁坏、损害”，flood名词，意为“洪水”；illness意为“疾病”选项C意为“困难”，故由句意答案选C；

16. A 【解析】由后边的那句话可以知道“有时候森林火灾对森林系统还是有帮助的”，故答案选A；

17. D 【解析】该句意为“森林火灾可以烧掉一些老树”，get rid of意为“去掉，除去”，故选D；而选项A为“取代，代替……”，选项B是“为……做好准备”，选项C为“对……有害处”，A、B、C均不符合题意；

18. C 【解析】此处是指经过火烧之后，有些种子厚厚的包衣被烧掉了，并掉到了地上，他们才有了生根发芽的机会。”故选C；A、B、D均不符合汉语意思；

19. B 【解析】句意为“通过这种方式，森林火灾不会传播到别的地区或者燃烧一大片森林。”cover本意为“涉及，覆盖”，此处是指不会造成大面积的森林被烧掉；选项A意为“揭露，发现”，选项D为“浪费”，都不符合题意；

20. C 【解析】此处是指森林大火过后，即使动物能够生存，他们也要经历饥饿的折磨，“因为森林中的食物被大火破坏了”，故答案选C；

21. B 【解析】此处讲一段时间之后，小的植物开始生长。动物在植物生长之后也重新回来了。“这又形成了一个(新的)食物链”，故答案选again，选项A、C、D均不符合句意；