用作形容詞：
較低的，下面的
A cloth should be spread under.
下面該鋪一塊布。
用作副詞：
1、在下面，在水下
As a matter of fact, Jesse's wife did soon go under.
事實上，杰西的妻子不久便降低了身份。
2、少于，小于，較年輕
Nearly half of mothers with children under five have a job.
孩子不滿5歲的媽媽中近一半有工作。
You should choose these jobs for those under 65.
你應該選擇適合65歲以下人士的工作。