动词不定式1．feel, hear, listen to 等感观动词和 have, let , make等使役动词后的补足语，在主动语态中，不定式不带to；在被动语态中，则必须带to。如：I often hear him sing the song. / He is often heard to sing the song.2. 不定式短语位于介词but, except, besides后时，如果这些介词之前有行为动词do 的各种形式，那么，这些介词后的不定式不带to，否则要带to。如：She could do nothing but cry. / It has no choice but to lie down and sleep.3. 不定式修饰的名词或代词与不定式逻辑上构成主谓关系时，不定式往往用主动形式。如：Have you got a key to unlock the door? (A key unlocks the door.)4. 不定式和它前面被修饰的名词或代词构成逻辑上的动宾关系，又和该句的主语构成逻辑上的主谓关系时，不定式常用主动形式。如：I have got a letter to write.( I write a letter.)5.如果不定式作表语形容词的状语，且和句中主语构成逻辑上的动宾关系时，不定式多用主动形式。如：The book is difficult to understand.( to understand the book)
关于连系动词后接不定式(1) 连系动词be后根据情况可自由地接不定式作表语：My dream is to be a scientist. 我的梦想是当一名科学家。All I could do was to wait. 我只能等。My plan was to go from London to Paris. 我计划从伦敦去巴黎。I was to have seen Mr Kay. 我本要去见凯先生的。(2) seem, appear, prove, continue, turn out, get, grow, come 等连系动词后也可接不定式(尤其是to be)作表语：She always seems to be sad. 她常常显得很忧伤。My advice proved to be wrong. 我的意见证明是错的。She appears to have many friends. 他好像有很多朋友。The weather turned out to be fine. 天气结果很好。Circumstances continue to be favorable. 情况仍然是有利的。He has grown to like studying English. 他渐渐喜欢学英语了。【注】若所接不定式为to be，通常可以省略。不过，若其后接的是表语形容词，则to be通常不宜省略。另外，连系动词look后能否接to be似乎尚有争论，不过，在现代英语中接to be的现象已较普遍。</p 产品：澳博培训供货总量：不限产品价格：议定包装规格：不限物流说明：货运及物流交货说明：按订单
