引导目的状语从句的从属连词。

主要的有 in order that, so that, in case, for fear等。如：

He raised his voice so that everyone could hear. 他提高了嗓音，以便每个人都能听见。

Take your umbrella (just) in case it rains. 带上雨伞，以防下雨。

She repeated the instructions slowly in order that he should understand.

她把那些指示慢慢重复了一遍好让他听明白。