《2025年系统集成新课程同步导学练测高中英语必修第二册》

2. it 作形式主语
It is the duty of every one of us to protect them for generations to come.
为后代来保护它们是我们每个人的责任。
【归纳拓展】
(1)It 为形式主语时的常用句式：
①It is/was + {adj. + to do(动词不定式作真正的主语)
{n.
②It is/was + {no use + doing(动名词作真正的主语)
{no good
{useless
③It + is/was + {adj. + that/what…(从句作真正的主语)
{n.
(2)在句中，如果 to do 有自己的逻辑主语，则用 It is + adj.(+ for/of sb.)+ to do sth.。如果表语形容词表示逻辑主语“人”的品质时，不定式的逻辑主语要用 of 引出；如果表语形容词只是说明不定式的特征，则用 for 引出不定式的逻辑主语。
It was his duty to attend to the matter.
处理这件事是他的责任。
It was difficult for her to make him understand her words.
对她来说，要他明白她所说的话是很困难的。
It's polite of people to knock at the door before entering.
人们在进门前先敲门是有礼貌的。
It's no good staying up too late.
熬夜没有好处。
【活学活用】
句子翻译
①他很难下定决心。
It is hard for him to make up his mind.
②你能帮助我们，真是太好了。
It is very kind of you to help us.
③我们不能去是个遗憾。
It's a pity that we can't go.
④尝试解释是没有用的。
It's no use trying to explain.

答案： 2.①It is hard for him to make up his mind.
②It is very kind of you to help us.
③It's a pity that we can't go.
④It's no use trying to explain.