It is ------ that ---- 句型
(1) It is + 名词 + 从句
It is a fact/an honour ---that+陈述语气从句
例：It is a fact that the earth moves around the sun.
地球围绕太阳转是事实。
It is a pity/shame/no wonder that+ 虚拟语气从句
例：It is a pity that he should not come. 他若不来可真是遗憾。
(2) It is + 形容词 + 从句
It is natural/important/necessary/strange that + 虚拟语气从句
例：It is important that enough money be collected to fund the project.
重要的是募集足够的钱，为这个项目提供资金。
It is obvious/apparent/clear that+ 陈述语气从句
例：It is clear that she doesn't like the dress at all.
这很清楚她一点儿也不喜欢这条裙子。
(3) It + 过去分词 + 从句
It is generally/commonly believed /accepted/thought/heldthat ...
+陈述语气从句
例：It is universally acknowledged that trees are indispensable to us.
全世界都知道树木对我们是不可或缺的。
It is suggested/ordered/desired/requested/decided that +虚拟语气从句
例句：It is suggested that we should hold a meeting next week.
建议我们下周开上会。
would have done = 本来就会去做某事而没做
could have done = 本可以做某事而没做
might have done本可以做而没做例：They ought to have apologized.他们本该道歉的。