哪些情況下不定式要省略to

1. 在let, make, have等使役動詞后用作賓語補足語的不定式必須省略to。如：

He had his son clean the car. 他叫他的兒子擦車。

Rain makes plants grow. 雨水使植物生長。

We can't let this go on. 我們不能讓這個情況繼續(xù)下去。

注：當(dāng)使役動詞用于被動語態(tài)時，要補上在主動語態(tài)中省略的to(主要是指make，let和have很少用于被動語態(tài))。如：

He was made to work long hours. 他們讓他長時間干活。

2. 在see, hear, observe, notice, feel, watch等感覺動詞后用作賓語補足語的不定式必須省略to。如：

I saw him stand up and go out. 我看見他站起來,然后就走了出去。

She noticed the man look [looking] at her a couple of times. 她注意到那個男人朝她看了好幾次。

I felt something crawl up my arm. 我覺得有什么東西順著我的胳膊向上爬。

注：若它們用于被動語態(tài)或用于完成式，則其后的不定式要帶to。如：

I noticed her to have come early. 我注意到她來得很早。

He was seen to enter the building. 有人看見那男子走進大樓。

另外注意，若動詞feel后用作賓語補足語的不定式為 to be，則要帶 to(其他情況不帶 to)。如：

They felt the plan to be unwise. 他們認為這個計劃不明智。

3. 在動詞help后用作賓語或賓語補足語的不定式可以不帶to：

I helped him (to) repair his bike. 我?guī)退�修自行�?/SPAN>

注：當(dāng)help用于被動語態(tài)時，不定式前的to不能省略。如：

The boy was helped by a woman to collect his scattered coins. 那男孩由一個婦女幫他撿拾散亂一地的錢幣。

另外，若 help 之后接一個較長的名詞詞組作賓語或其中的不定式所表示的動作主語不直接參加，則不定式通常帶to。如：

Help the little boys at the back of the hall to carry the chairs out. 請幫大廳后面那些小男孩把椅子搬出去。

These tablets will help you to sleep. 這些藥片將對你的睡眠有幫助。