hairline crack

There 's a hairline crack in the rim of that jar

那只罐子的口沿有条极细的裂缝。

Basing on the above tests , we think that the hairline crack is induced by the remained deep vibration mark of casting slab .

认为，发裂缺陷是板坯连铸时产生的较深沟形振痕残余造成的。

He seemed to be catching on nothing : propping his boot on a pimple , gripping a " smear " or a hairline crack , freeing both arms from the rock to make a lunge .

他似乎并没有什么可靠的支撑点：踩的地方只是一个小突起；抓的地方只是一块粗糙平面或是一条狭细的裂缝；身子向前猛扑时，双手会脱离岩壁在空中。