原形不定式

（1）使役動詞，表示 使 / 讓...

1.  have, make, let 做使役動詞，構成形式為： have / make / let + 賓語 + v
    He made me laugh
    I let him go 
    Please have him come here

2. get 和 help 都做使役動詞，get的使役動詞句為 get + 賓語 + to + v, help 的使役動詞句為 help + 賓語 + （to）+ v, help翻譯的時候翻譯為 ‘' 幫助 '
    I can't get anyone to do the work properly
    I helped him (to) repair the car

3.  上面倆個所有使役 + 賓語 + 過去分詞， 表示讓某物 / 人 被別人...
    I must get my hair cut 
    He couldn't make himself heard
    Can you get the work finished in time ?

（2）感官動詞 see / watch / observe / notice / hear / smell / taste / feel + 賓語 + 動詞原形 / 現在分詞（a: + 動詞原形，表示動作的真實性；b: +現在分詞，表示動作的連續性，進行性）

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

1. 和使役動詞相似，感官動詞可接過去分詞， 感官動詞 + 賓語 + 過去分詞  表示被動含義  表示賓語被怎么樣了
    John saw the man knocked down by the car