Concavities
n. 凹面, 成凹形( concavity的名词复数 )
🗣️ 情景例句
Excuse me, do you know...?
打扰一下，你知道...？
He guessed the train would come in early.
他猜想火车会很早到达。
There are some boats on the river.
河上有几艘船。