原形不定式

（1）使役动词，表示 使 / 让...

1.  have, make, let 做使役动词，构成形式为： have / make / let + 宾语 + v
    He made me laugh
    I let him go 
    Please have him come here

2. get 和 help 都做使役动词，get的使役动词句为 get + 宾语 + to + v, help 的使役动词句为 help + 宾语 + （to）+ v, help翻译的时候翻译为 ‘' 帮助 '
    I can't get anyone to do the work properly
    I helped him (to) repair the car

3.  上面俩个所有使役 + 宾语 + 过去分词， 表示让某物 / 人 被别人...
    I must get my hair cut 
    He couldn't make himself heard
    Can you get the work finished in time ?

（2）感官动词 see / watch / observe / notice / hear / smell / taste / feel + 宾语 + 动词原形 / 现在分词（a: + 动词原形，表示动作的真实性；b: +现在分词，表示动作的连续性，进行性）

    I saw him work in the garden yesterday
    I saw him working in the garden yesterday

1. 和使役动词相似，感官动词可接过去分词， 感官动词 + 宾语 + 过去分词  表示被动含义  表示宾语被怎么样了
    John saw the man knocked down by the car