fall·off /ˈfɔˌlɔf/
  下降,減退;分開,排出
  falloff
       n : 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, drop-off, falling off]