drop-off /ˈdrɑpˌɔf/
陡坡
drop-off
n 1: 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" [syn: slump,
slack, falloff, falling off]
2: a steep high face of rock; "he stood on a high cliff
overlooking the town"; "a steep drop" [syn: cliff, drop]
3: a change downward; "there was a decrease in his temperature
as the fever subsided"; "there was a sharp drop-off in
sales" [syn: decrease, lessening] [ant: increase]