1。It is essential that he___in extracurricular activities。
 rticipate  rticipates C。will participate
 all participate
\\\\ A participate
It is essential that 是虚拟语气句式，that 的从句中 用 should + 动词原形，而should 可省略。
  
2。Research findings show we spend about two hours dreaming every night,no matter what we__during the day。
 ould have done B。
  would have done
 y have done  st have done
\\\\\\\ may have done
研究发现显示，每天夜里我们花大约2个小时做梦，不论我们在白天期间可能做了什么。
只有选 C 句子的意思才是通顺的。
  
3。It was impossible to avoid___by the stormy weather。
  be much affected  ing much affected
C。having much affected   have been much affected
\\\\\B being much affected
avoid 后 接动名词，不能接不定式。
  所以 A D 错误。而C是主动句式，不是被动句式，不符合句子的意思。
4。Although he knew little about the large amounts of work done in the field,he succeeded___other more well-informed experimenters failed。
  
A。which  at C。what D。where
\\\\\\\ D where
虽然他对这个领域里的大量工作 知之甚少，但是他在其他更家 内行 的实验者失败的问题上 取得了成功。
succeed后要接状语从句，表示 在什么地方什么问题上 成功了。
  只有 where 才能构成状语从句。
 
5。The king commanded that enough money___to fund the project。
  collected  st be collected
  collected  n be collected
\\\ A be collected
 command 后得that 从句中要使用虚拟语气 should+动词原形。
  should 可省略。
6。Frankly speaking,I'd rather you___anything about it for the time being。
A。didn't do B。haven't done  n't do D。
  have done
\\\\\\\ A didn't do
would rather + that 从句，要使用虚拟语气，that 从句中的动词 使用 过去式。
。