请较一题

九山环一湖

In 2000, a mere two dozen products accounted for half the increase in spending on prescription drugs, a phenomenon that is explained not just because of more expensive drugs but by the fact that doctors are writing many more prescriptions for higher-cost drugs.

a phenomenon that is explained not just because of more expensive drugs but by the fact that doctors are writing

a phenomenon that is explained not just by the fact that drugs are becoming more expensive but also by the fact that doctors are writing

a phenomenon occurring not just because of drugs that are becoming more expensive but because of doctors having also written

which occurred not just because drugs are becoming more expensive but doctors are also writing

which occurred not just because of more expensive drugs but because doctors have also written

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

这里的IT是什么用法啊 ?

tianwan

B：  A不对称，D，E的which指代句子不可以，C的having不能做定语。

D：A，B的which指代句子，C的them的指代，E少了a连词连接2个并列的句子。

九山环一湖

第一题的not only ... but also 的结构也不完整啊?

tianwan

以前讨论过，not just的just=only。记住这个变态的结构吧，没有为什么。