1、(使)堅(jiān)硬，硬化。
This additive hardens the cement in an hour
這種添加劑會(huì)使水泥在一小時(shí)之后變硬。
The bread will harden if you don't cover it.
這種面包如果不蓋起來(lái)就會(huì)變硬。
2、使變得冷酷無(wú)情，變得冷漠，麻木不仁的
Years of reporting on wars hardened them to human suffering。
多年來(lái)對(duì)戰(zhàn)爭(zhēng)的報(bào)到使得他們對(duì)人類的痛苦變得麻木不仁了。
His eyes hardened when he saw her.
看到她時(shí)，他的眼光變得很冷漠。
harden your heart 硬起心腸，不心軟
3、(使)堅(jiān)定
Obama appeared to have hardened his line on Europe.
看來(lái)奧巴馬更堅(jiān)定了他在歐洲問(wèn)題上的態(tài)度。
