lest

lest [lest] conj.

1. ■ [所连接的状语从句里常用should或原形动词]以免; 生怕; 唯恐

2. ■ [=that][用于fear, worry等词之后起连接作用, 无实际意义]

Be careful lest you fall from that tree. 要当心, 以免从树上摔下来。

I was afraid lest he might come too late. 我怕他来得太晚。