懸崖勒馬 [ㄒㄩㄢˊ ㄧㄞˊ ㄌㄜˋ ㄇㄚˇ; xuan2 yai2 le4 ma3] lit. to rein in the horse at the edge of the precipice (idiom); fig. to act in the nick of time ◄ ►