后面接疑问词引起的短语或从句

help  do  sth

wish后的宾语从句

用过去时指现在，表达与事实情况相反的愿望；

用过去完成时表示过去，因不能挽回，常有懊悔的意思；

用would/could/should/might+V.原型指将来，表示可能实现的愿望（可能性较低，接近一种客气 的请求）

It's time to do something.或It's high time 真是到了什么的时候

虚拟语气

条件从句省略if，采用倒装语序

Subjunctive Mood虚拟语气

与实际相反，假想的情况，主观愿望

动词时态：现在，过去。未来

条件句

if，unless,suppose3引导

if+ 主语+过去时

if+主语+had+过去分词+过去分词

if+主语+should/were to+原型

if+主语+过去时

If it had not been for your help,I couldn't have achieved this.

But for your help, I could not have achieved this.

条件从句省略if，采用倒装语气

should+动词原形

 They expressed the wish that tax(should) be abolished.同位语从句

The doctor advised that he (should) quit smoking. 宾语从句

由由