刀刃的英文：
knife edge
crucial point

A keen Blade
锋利的刀刃

The knife Blade is wearing away.
刀刃正受磨损。

The blade slashed his leg(open).
刀刃把他的腿划(破)了.

He sharpened the edge of his knife on a grindstone.
他在磨石上磨快了他的刀刃。

The edge of this knife is too dull to cut the bread.
这把刀的刀刃很钝，无法切面包。

The blades of the swords had rusted away.
刀刃已经生锈了。

Be careful of the sharp blade !
当心这锋利的刀刃！

Please sharpen the edge of this knife.
请把这刀刃磨快。

Good steel should be used for the making of the sword's blade;Let the best horse leap the hedge first．
好钢使在刀刃上。

"Roman swords had a short, flat blade and a hilt distinct from the blade."
罗马军刀刀刃短而平，刀柄明显区别于刀刃。

The killer stabbed him with a knife/stabbed a knife into him.
凶手用刀刺他.

The knife easily cut into the cake.
刀一下子就切进了蛋糕。

The intruder whipped out a knife.
闯进来的人突然掏出一把刀来。

The number of incoming edges is equal to the number of outgoing edges
进入的线数等于离去的线数。

pipe edges sewing machine
滚边缝纫机

Sloth turneth the edge of wit
懒惰会磨去才智的锋芒

Salt is a crucial ingredient in cooking.
盐是烹调的一种重要材料。

The lack of clarity is especially crucial.
缺乏透明度是关键。

The foreign market was increasingly crucial.
国外市场越来越重要了。