1、master

主人;雇主;老板

My master ordered me not to deliver the message except in private.

我的主人命令我务必私下里传递消息。

In 1777 several northern states encouraged white masters to free their slaves for military service.

1777年，北方的几个州鼓励白人奴隶主解放奴隶，让他们参军。

专家;能手;高手

She was a master of the English language.

她是英文高手。

He is a master at blocking progress.

他特别擅长充当拦路虎。

掌握;精通

Duff soon mastered the skills of radio production.

达夫很快掌握了广播节目制作的技能。

Students are expected to master a second language.

学生应该掌握一门第二语言。

2、friction

矛盾;不和;争执

Sara sensed that there had been friction between her children.

萨拉感觉到她的孩子之间有过争执。

The plan is likely only to aggravate ethnic frictions.

这一方案很有可能只会加剧种族冲突。

摩擦力

The pistons are graphite-coated to reduce friction.

活塞上涂了一层石墨以减小摩擦力。