(后跟動詞原形，構(gòu)成不定式，可用作主語、賓語、表語、復(fù)合賓語、狀語等，還可以單獨(dú)使用)(used before a verb to indicate the infinitive;the infinitive can be used as a subject，an object，a predicative，a compound object，an adverbial，etc;it also can be used alone when the infinitive is understood)：T～make mistakes is natural. 犯錯誤是很自然的(事情)。It's important for us～learn English. 對我們來說，學(xué)英語是非常重要的。want～finish the work on time 想按時完成工作;want～invest 打算投資;know what/how～do知道做什么/怎么做;used～do sth過去常常做某事;They are～be married soon. 他們很快就要結(jié)婚了。ask sb～come 邀請某人前來;persuade sb not～do sth 勸某人不做某事;leave early～catch the train 早點(diǎn)動身去趕火車;She opened her eyes～find her sister standing beside her. 她睜開眼睛發(fā)現(xiàn)她的姐姐站在身旁。T～tell you the truth，I don't know what the answer is. 實(shí)話告訴你，我不知道答案。I asked him～go with us but he refused～. 我讓他和我們一起去，但他拒絕了。