🧩 词语组成解析
marsh
[mɑrʃ]
n. 沼泽，湿地;
fern
[fə:n]
n. <植>羊齿植物，蕨类植物;
🗣️ 情景例句
How is everyone in your family?
全家都好吗？
Do you know what the population of Japan is?
你知道日本的人口是多少吗？
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。