非謂語動詞之動詞不定式
不定式是一種非謂語動詞，由"to+動詞原形"構成***使用時有時不帶to***，在句子中不能單獨作謂語。它具有名詞、形容詞和副詞的特徵，同時又保持了動詞的某些特徵，在句中可以作主語、表語、賓語、定語、狀語和補足語。不定式的否定結構由不定式符號to前加not構成，即"not to+動詞原形"。考試中的難點在於時態***一般式to +v、進行式to be +v-ing、完成式to have +v-ed、完成進行式to have been +v-ing***、語態***主動和被動to be +v-ed / to have been +v-ed***和帶或不帶to的問題。
1.接不定式作賓語的動詞和動詞短語
1***下列動詞直接跟帶to的不定式作賓語：afford, agree, appear, arrange, ask, attempt, bear, beg, begin, care, choose, claim, consent, dare, decide, demand, desire, determine, expect, fail, fear, forget, happen, hate, help, hesitate, hope, incline, intend, learn, like, love, manage, mean, neglect, offer, plan, prefer, prepare, pretend, promise, propose, refuse, regret, remember, seem, start, swear, trouble, try, undertake, want, wish等。例如：
he has planned to study french next year.他打算明年學法語。
2***下列動詞可以接"疑問代詞who, whom, what, which,疑問副詞when, where, why, whether, how +to不定式"作賓語：ask, consider, decide, discover, explain, find out, forget, guess, imagine, know, learn, observe, remember, show, tell, think, understand, wonder等。例如：
she can’t decide what to do.她決定不了該做什麼。
該結構"疑問代詞/副詞+to不定式"還可以作主語、表語、賓語、介詞賓語、定語等。如：
what worries me most is what to say at the meeting.使我著急的是不知道在會上說些什麼。
3***believe, consider, feel, find, judge, make, think等動詞後的賓語如果是不定式，補語是形容詞或名詞時，常用it作先行賓語，把不定式後置。例如：
i found it impossible to answer all the questions within the time given.我發現在限定時間內回答所有的問題是不可能的。
1.接不定式作賓語的動詞和動詞短語
1***下列動詞直接跟帶to的不定式作賓語：afford, agree, appear, arrange, ask, attempt, bear, beg, begin, care, choose, claim, consent, dare, decide, demand, desire, determine, expect, fail, fear, forget, happen, hate, help, hesitate, hope, incline, intend, learn, like, love, manage, mean, neglect, offer, plan, prefer, prepare, pretend, promise, propose, refuse, regret, remember, seem, start, swear, trouble, try, undertake, want, wish等。例如：
he has planned to study french next year.他打算明年學法語。
2***下列動詞可以接"疑問代詞who, whom, what, which,疑問副詞when, where, why, whether, how +to不定式"作賓語：ask, consider, decide, discover, explain, find out, forget, guess, imagine, know, learn, observe, remember, show, tell, think, understand, wonder等。例如：
she can’t decide what to do.她決定不了該做什麼。
該結構"疑問代詞/副詞+to不定式"還可以作主語、表語、賓語、介詞賓語、定語等。如：
what worries me most is what to say at the meeting.使我著急的是不知道在會上說些什麼。
3***believe, consider, feel, find, judge, make, think等動詞後的賓語如果是不定式，補語是形容詞或名詞時，常用it作先行賓語，把不定式後置。例如：
i found it impossible to answer all the questions within the time given.我發現在限定時間內回答所有的問題是不可能的。