fall off
decrease in quantity or quality 数量或质量下降:Attendance at my lectures has fallen off considerably.听我讲课的人已大大减少了.
* It used to be my favourite restaurant but the standard of cooking has fallen off recently.那是我以前最喜欢的饭馆,但近来烹饪水平已大不如前了.
fall down
be shown to be false or inadequate; collapse 显示不实或不足; 崩溃; 失败:The plan fell down because it proved to be too expensive.这项计划因费用过高而告吹.
fall down on sth (infml) fail to do sth properly or successfully 没有把某事做好:fall down on one's promises 未履行自己的诺言
* He fell down on the job.他未能把这件工作做好.
