名詞 knife-edge:

1. a narrow boundary
2. the sharp cutting side of the blade of a knife
   同義詞：knife edge, cutting edge

1. The success of the project is still very much on a knife-edge.
   這一項(xiàng)目的成敗目前仍處?kù)蛾P(guān)鍵時(shí)刻。
2. He's on a knife-edge about his exam results.
   他對(duì)考試成績(jī)十分擔(dān)心。

knife-edge

n.（名詞）
A sharp cutting edge.
刀刃，鋒刃：鋒利的、切割的刀刃
A sharp, narrow edge or border:
搖擺不定的處境；極微妙的狀態(tài)：鋒利而狹窄的邊或邊緣：
例句：
.saying lines that teeter on the knife-edge between literature and lunacy.(Vincent Canby)
.吟詠著處在文學(xué)與瘋?cè)藝艺Z(yǔ)徘徊的詩(shī)句.(文森特·坎比)

A wedge of metal used as a low-friction fulcrum for a balancing beam or lever.
刃形支承：一種楔形金屬，用作平衡木或杠桿的摩擦小的支撐物