Praetrsonics
极超短波晶体声学, 特超声(学)
🗣️ 情景例句
Then an adult must sign for you.
那就必须有一位成年人来替你签字。
My cousin is a member of a riding club, He seems riding.
我的表兄是一个骑马俱乐部成员，他似乎很喜欢骑马。
They will arrive in half an hour.
他们将于半小时之内到达。