非谓语动词作主语,常用不定式作主语的句型,It is/was + 名词 + to do sth,It is/was + 形容词( + for sb./ of sb.) + to do sth,It takes sb. sometime to do sth,Its our duty to take good care of the old,It is difficult for us to finish writing the composition in an hour,It takes me two hours to finish the work,常用动名词作主语的句型,It is/was,no use/ good,not any use/ good,of little use/ good,worth,doing sth,It is no use complaining about something in our daily life repeatedly,It is no good speaking ill of others,It is worth making an appointment before you go