If you've ever seen Superman, Superman has a chin of steel.

如果您见过超人，就会知道超人的下巴是钢铁般的。

Leonardo also mentions someone having a " weak (weak) chin." A " weak chin" is a chin that you almost don't notice, a chin that doesn't seem to be very distinctive, almost as though it's part of your neck or that you don't have a chin.

莱昂纳多还提到有人有“弱（弱）下巴” 。 “弱下巴” 是你几乎不会注意到的下巴，看起来不是很有特色的下巴， 就好像它是你脖子的一部分或者你没有下巴。