1. It is important that... ……是很重要的. [主语从句使用虚拟语气]

It is important that something be done before it's too late.
在事情变得不能挽回之前采取一些行动是很重要的.

2. It's long been my dream to...……一直是我的梦想.

It's long been my dream to make a speech in English. 用英语发表演讲一直是我的梦想.

3. It is (very /not) likely that... (很/没)有可能…….

It is likely that it will rain this afternoon. 今天下午很有可能下雨.

4. It is (not) necessary to...……是(没)有必要的.

1) I think it is necessary to look before you leap. 我觉得三思而后行是有必要的.
2) When invited, it is not necessary for you to bring anything with you. 去做客不一定非要带礼物.

5. It is no use doing sth. 做某事是毫无用处的.

It is no use talking without doing. 光说不做是没有用的.

6. It is not unusual for sb. to do... 某人做……不足为奇.

It is not unusual for the British people to drink tea. 英国人喝茶不足为奇.

7. It is possible /impossible to...……是(不)可能的.

It's impossible to predict the outcome of the game.
要预知比赛结果是不可能的. [ outcome n. 结果;成果]

8. It is dangerous to......危险.

It is dangerous to explore the jungle with so many wild animals around.
在很多野兽出没的丛林里探险是危险的.

9. It is (rather) common to do... ……(相当)普遍.

It is rather common for women to hold important positions in companies now.
如今女性在公司担任重要职位相当普遍.

10. It is reported that...据说……./据报导…….

It is reported that the world famous football star will come to China next year.
据说那位闻名世界的足球明星明年要来中国.