不定式
1.不定式做主語
(1)引導(dǎo)邏輯主語的介詞：不定式的邏輯主語一般由介詞for引導(dǎo),但下列表示人的性格行為特征的形容詞做表語時(shí), 不定式的邏輯主語則由of引導(dǎo)：
absurd, bold, brave, courageous, careful, careless, clever, wise, foolish, silly, stupid, good, nice, kind, thoughtful, considerate, greedy, generous, honest, modest, polite, rude, cruel, selfish, lazy, wicked, wrong。如：
Experts say walking is one of the best ways for a person to stay healthy.
It’s clever of you to have invented such a device.
2不定式做主語補(bǔ)足語：
掌握常用不定式做主語補(bǔ)足語的句型。注意不定式表示的動(dòng)作發(fā)生的時(shí)間，并采用相應(yīng)形式。如：
be said / reported / thought / believed / known / supposed + to do sth.