[求助]OG34-2 以大推小错在哪了?

littlebriton

一个是ECOSYSTEM IN DRY LAND， 一个是MARINE ECOSYSTEM，不是一个范畴的

dickbeckham

斑竹快来帮忙啊!!!急急急

dickbeckham

再顶!

dickbeckham

斑竹来看一下啊!!!

dickbeckham

自己先顶一下!

dickbeckham

34.Coral reefs are one of the most fragile, biologically

complex, and diverse marine ecosystem on Earth. This

ecosystem is one of the fascinating paradoxes of the bio-

sphere: how do clear, and thus nutrient-poor, waters sup-

(5) port such prolific and productive communities? Part of the

answer lies within the tissues of the corals themselves.

Symbiotic cells of algae known as zooxanthellae carry out

photosynthesis using the metabolic wastes of the coral

thereby producing food for themselves, for their corals,

(10) hosts, and even for other members of the reef community.

This symbiotic process allows organisms in the reef com-

munity to use sparse nutrient resources efficiently.

Unfortunately for coral reefs, however, a variety of

human activities are causing worldwide degradation of

(15) shallow marine habitats by adding nutrients to the (water.

Agriculture, slash-and-burn land clearing, sewage disposal

and manufacturing that creates waste by-products all

increase nutrient loads in these waters. Typical symptoms

of reef decline are destabilized herbivore populations and

(20)an increasing abundance of algae and filter-feeding

animals.

Declines in reef communities are consistent with observa-

tions that nutrient input is increasing in direct proportion to

growing human populations, thereby threatening reef com-

(25) munities sensitive to subtle changes in nutrient input to

their waters.

214. The passage suggests which of the following about coral reef communities?

(A) Coral reef communities may actually be more likely to thrive in waters that are relatively low in nutrients.

(B) The nutrients on which coral reef communities thrive are only found in shallow waters.

(C) Human population growth has led to changing ocean temperatures, which threatens coral reef communities.

(D) The growth of coral reef communities tends to destabilize underwater herbivore populations.

(E) Coral reef communities are more complex and diverse than most ecosystems located on dry land.

作者明明说了"Coral reefs are one of the most fragile, biologically

complex, and diverse marine ecosystem on Earth."为什么不能说than most ecosystems located on dry land.从大范围推小范围有什么错???