Concavities
n. 凹面, 成凹形( concavity的名词复数 )
🗣️ 情景例句
I think I've seen you before, You look very familiar.
我想我以前在哪里见过你，你看起来非常面熟。
No time like the present.
只争朝夕。
The characters on the paper were white, and the rest of the paper was black.
纸上的汉字呈白色，其余部分成黑色。