名詞 drop off:

1. a noticeable deterioration in performance or quality
   同義詞：slump, slack, drop-off, falloff, falling off
2. a steep high face of rock
   同義詞：cliff, drop, drop-off
3. a change downward
   同義詞：decrease, lessening, drop-off

動詞 drop off:

1. fall or diminish
2. change from a waking to a sleeping state
   同義詞：fall asleep, dope off, flake out, drift off, nod off, doze off, drowse off
3. leave or unload, especially of passengers or cargo;
   同義詞：drop, set down, put down, unload, discharge
4. retreat
   同義詞：fall back, lose, fall behind, recede
5. get worse
   同義詞：slip, drop away, fall away

1. Interest in the book began to drop off.
   人們對這本書的興趣開始減退了。
2. Sales dropped off in the fourth quarter.
   銷售量在第四個季度減少了
3. I drop off and miss the end of the film.
   我打了個盹兒，把影片的結尾給錯過了。
4. Business dropped off sharply during the recession.
   在經濟衰退期間，生意大大減少了。