大全-16-4

4.     Two experimental garden plots were each planted with the same number of tomato plants. Magnesium salts were added to the first plot but not to the second. The first plot produced 20 pounds of tomatoes and the second plot produced 10 pounds. Since nothing else but water was added to either plot, the higher yields in the first plot must have been due to the magnesium salts.

Which of the following, if true, most seriously weakens the argument above?

(A) A small amount of the magnesium salts from the first plot leached into the second plot.

(B) Tomato plants in a third experimental plot, to which a high-nitrogen fertilizer was added, but no magnesium salts, produced 15 pounds of tomatoes.无关对象

(C) Four different types of tomatoes were grown in equal proportions in each of the plots.补充信息，无关

(D) Some weeds that compete with tomatoes cannot tolerate high amounts of magnesium salts in the soil.（E）支持

(E) The two experimental plots differed from each other with respect to soil texture and exposure to sunlight.他因

我感觉削弱的思路有2

1 他因 就是E

2 盐不会导致高产 就是A

我不理解为何A不对呢

谢谢

1 他因 就是E

2 盐不会导致高产 就是A

你的这个思路没问题，关键是A说的是A small amount of ，所以构不成削弱。

这么老的帖子都翻出来，ForeverDark你真行。

D选项不是削弱而是增强。他提出一些和tomato争夺营养的weeds无法忍受大量的magnesium salts 。因为第一个plot里有大量的magnesium salts，所以weeds无法生长，这样子第一个plot的tomato在没有竞争的情况下自然会长的更好。所以D是增强而不是削弱。

哦，明白了！多谢楼上的朋友！