Q2:

Scientists are discussing ways to remove excess carbon dioxide from the atmosphere by increasing the amount that is absorbed by plant life. One plan to accomplish this is to establish giant floating seaweed farms in the oceans. When the seaweed plants die, they will be disposed of by being burned for fuel.

Which of the following, if true, would indicate the most serious weakness in the plan above?

1. Some areas of ocean in the Southern Hemisphere do not contain sufficient nutrients to support large seaweed farms.
2. When a seaweed plant is burned, it releases an amount of carbon dioxide comparable to the amount it has absorbed in its lifetime.
3. Even if seaweed farms prove effective, some people will be reluctant to switch to this new fuel.
4. Each year about seven billion tons of carbon dioxide are released into the atmosphere but only about five billion tons are absorbed by plant life.

Seaweed farms would make more money by farming seaweed to sell as nutritional supplements than by farming seaweed to sell as fuel.

我选b,但是不确定，好像d也对，指教！谢谢！

我认为B,因为它和文章相关.D错,虽然看似对,但实际上和文章里说得这个计划是没有关系得,是个一般事实得叙述,属于无关.

i vote for B. D is fully wrong.

if the amount of carbon dioxide released by the process of

burning a seaweed plant is comparable to the amount it stored in its

lifetime, as B tells us, the plan advocated in the passage to decrease

the amount of carbon dioxide in the atmosphere will certainly fail.

choice D decribes a fact that necessitates the plan to remove

excess carbon dioxide in the atmosphere. but it does not weaken the

conclusion that the plan will be effective.