Supererogation
n. 职责以外的工作
🗣️ 情景例句
Yes, you have a point there.
对，你说的这一点有道理。
Stereo set playing a record
放着唱片的立体声唱机
and by measuring the time interval between the taps and the receipt of the echoes, the depth of the sea at that point can be calculated.
测出回声间隔的时间，便可算出该处海洋的深度。