Improficiency
不良成绩
🗣️ 情景例句
and for the furniture needed,
和购买必需家俱，
Don't mention it.
不必客气。
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。