不定式或不定式短語作主語時,常用it作形式主語,避免頭重腳輕,這時大多構成“It is + 形容詞(+for sb.)不定式”結構.
It is impossible for him to give up smoking.
但也可能用於其它句型,如：
It took Professor Chomsky near a decade to finish writing this book.
值得注意的是：
在It is adj for sb to do sth 句型中,如果做表語的形容詞是表現人的內在的性質特點的,如：honest,cruel,warm-hearted,stupid,nice,kind,careful,considerate,selfish,mean(小氣的）等,需用of sb to do sth.如：
It is very kind of you to have come all the way to the airport to see me off.
It is very careless of you to have made so many mistakes in this exam.
不定式或不定式短語作主語時,常用it作形式主語,避免頭重腳輕,這時大多構成“It is + 形容詞(+for sb.)不定式”結構.
It is impossible for him to give up smoking.
但也可能用於其它句型,如：
It took Professor Chomsky near a decade to finish writing this book.
值得注意的是：
在It is adj for sb to do sth 句型中,如果做表語的形容詞是表現人的內在的性質特點的,如：honest,cruel,warm-hearted,stupid,nice,kind,careful,considerate,selfish,mean(小氣的）等,需用of sb to do sth.如：
It is very kind of you to have come all the way to the airport to see me off.
It is very careless of you to have made so many mistakes in this exam.