「一落千丈」

(pos:動詞)
<explanation>
yue:好短時間內就差咗好多
eng:to suffer from a drastic decline; literally "to drop a thousand in one fall"
<eg>
yue:沙士期間，食肆生意一落千丈。 (saa1 si2 kei4 gaan1, sik6 si3 saang1 ji3 jat1 lok6 cin1 zoeng6.)
eng:During the breakout of SARS, restaurants earned a lot less.