Concavities
n. 凹面, 成凹形( concavity的名词复数 )
🗣️ 情景例句
Hi, Grandpa.
嗨， 爷爷。
Since we need the goods urgently, we must insist on express shipment.
由于我方急需这批货物，我方坚持使用快递装运。
Good evening, Uncle Wang!
王叔叔，晚上好！