[求助]gwd-5-34请教！

yanginottawa

Q34:

Many entomologists say that campaigns to eradicate the fire ant in the United States have failed because the chemicals that were used were effective only in wiping out the ant’s natural enemies, which made it easier for them to spread.

which made it easier for them

which makes it easier for it

thus making it easier for them

thus making it easier for the ant

thereby, it was made easier for the ant

答案D，我选了B，which在这里难道不是指代“because the chemicals that were used were effective only in wiping out the ant’s natural enemies”整个一句？D中的thus又是起到什么作用？应该注意thus的什么用法？没有找到以前的讨论贴，望指教！谢谢！

zs8373

which 不可以指代整个句子.其他的我也不明白为什么

yanginottawa

谢谢啊，竟然忘了这么常用的语法点。

miaoyu2

it指代什么呢？

足球幽灵

which的用法，排除AB；them指代不清，C错；E，run on.