vt.

1. 使平坦；弄平
   The workman flattened a piece of metal by hammering it.

   工匠将一块金属锤平。

2. 击倒，击败；摧毁
   The storm flattened the crops.

   暴风雨使庄稼都倒下来了。

vi.

1. 变平坦[（+out）]
   The lump had almost flattened out.

   这肿块差不多消失了。

v.

1. make or become flat or flatter.
2. press (oneself) against a surface.
3. raze to the ground.
4. informal strike (someone) so as to make them fall down.
5. Music  lower (a note) in pitch by a semitone.