long的名词形式：length：n.长;长度;(持续)时间的长短;(书或文件等的)篇幅;(电影的)片长

复数： lengths

记忆技巧：leng〔= long长〕+ th 性质，状态 → 长度

相关介绍

We discussed shortening the length of the course.

我们就缩短这门课程的时限进行了讨论。

Each class is 45 minutes in length.

每一节课为45分钟。

She got a headache if she had to read for any length of time.

她读书时间长了就头疼。

The average length of a woman's menstrual cycle is 28 days.

妇女的平均月经周期是28天。