1、drop out

退学;退出(比赛等)

He'd dropped out of high school at the age of 16.

他 16 岁的时候就从中学退学了。

She dropped out after 20 kilometres with stomach trouble.

20 公里后她因胃痛而退出了比赛。

拒绝接受传统规范;离经叛道;摈弃社会习俗

She encourages people to keep their jobs rather than dropping out to live in a commune.

她鼓励人们坚持工作而不是离经叛道地去过公社生活。

2、concrete

混凝土

The posts have to be set in concrete.

这些柱子必须用混凝土固定。

They had lain on sleeping bags on the concrete floor.

他们就躺在铺在混凝土地面上的睡袋上。

具体的;确实的

He had no concrete evidence.

他没有确凿的证据。

There were no concrete proposals on the table.

没有具体的提议可供讨论。

(计划或观点)固定的，不变的

As Mr Blunkett emphasised, nothing is yet set in concrete.

正如布伦基特先生所强调的，一切都还没有定下来。