[求助]last-16-2-16

16. In their native habit, amaryllis plants go dormant when the soil in which they are growing dries out during the dry season. Therefore, if amaryllis plants kept as houseplants are to thrive, water should be withheld from them during part of the year so that the plants go dormant. Which one of the following is an assumption on which the argument depends?

(A) Most kinds of plants go dormant at some time or other during the year.

(B) Amaryllis are more difficult keep as houseplants than other kinds of plants are.

(C) Water should be withheld from amaryllis plants kept as houseplants during the exact time of year that corresponds to the dry season in their native habitat

(D) Any amaryllis plant that fails to thrive is likely to have been dormant for too short a time.

(E) Going dormant benefits amaryllis plants in their native habitat in some way other than simply preventing death during overly dry periods.

给的参考答案是E。

我认为，这里的assumption 是dry导致dormant。而且，对E取非得Going dormant benefits amaryllis plants in their native habitat in some way of preventing death during overly dry periods.这并不能削弱结论啊

请牛牛指教

I am not Niu Niu, but I'll give it a try. It is kind of a tough question.

To negate E: Going dormant does not benefit amaryllis plants in their native habitat in some way other than simply preventing death during overly dry period. If this is true, look at conclusion, when why do we have to withdraw water to make the plants dormant, because to make it dormant does not offer any benefit, the necessary condition in the conclusion has been weakened, therefore E is the right answer.  

If the conclusion contains a condition, to weaken a conclusion, either find an alternative sufficient condition, or to show the necessary condition does not have to happen for sufficient condition to happen.

Hope it helps.