lichard \$m[1]:想請問各位大大 為何A選錯誤
By the same techniques used for genetically enhancing plants, making them disease- or pest-resistant, researchers have been able to increase the amount of protein in potatoes, sweet potatoes, and tobacco.
A.By the same techniques used for genetically enhancing plants, making them
C.Employing the same techniques used to genetically enhance plants so that they are
若是C選的 話 那麼used to 不是表示（過去習慣於嗎 ）？？
這樣不是跟原本題目used for 表示（ 被用來作某目的的 意思 ） 不一樣了 嗎??
from longman
use something for (doing) something
They were using animals for scientific experiments.
Bob uses the van for picking up groceries.
還是A選是因為making them....在句子中間以致不能判斷誰是主詞嗎 ??
請各位大師幫忙解惑一下 ^^
C的還原應該是
Employing the same techniques（which are） used to genetically enhance.......
而不是你講的"used to "(過去習慣於)
以下的解釋我就不確定了，CD是有人這樣說的：
作主詞時，只能by doing不能by sth
有誰可以印證一下這講法嗎？
