我的脑子就像一块钢，很难在上面划上东西，但是一旦在上面留下痕迹几乎很难将它抹去。

My mind is like a piece of steel - very hard to scratch anything on it, and almost impossible after you get it there, to rub it off.

youdao

这个东西甚至比钢还硬。

This is even/much harder than steel.

youdao

这个东西甚至比钢还硬。

This is even/much harder than steel.

youdao