drop-off 是什么意思

	n. 1.陡坡。 2.衰减。

	a change downward; "there was a decrease in his temperature as the fever subsided"; "there was a sharp drop-off in sales" 同义词：decrease, lessening,
	a steep high face of rock; "he stood on a high cliff overlooking the town"; "a steep drop" 同义词：cliff, drop,
	a noticeable deterioration in performance or quality; "the team went into a slump"; "a gradual slack in output"; "a drop-off in attendance"; "a falloff in quality" 同义词：slump, slack, falloff, falling off,

drop-off是什么意思