使变平（flat的过去式、过去分词）

Flat \Flat\, v. t. [imp. & p. p. {Flatted}; p. pr. & vb. n.
{Flatting}.]
1. To make flat; to flatten; to level.

2. To render dull, insipid, or spiritless; to depress.

Passions are allayed, appetites are flatted.
--Barrow.

3. To depress in tone, as a musical note; especially, to
lower in pitch by half a tone.