Ballvalve
球型人造瓣膜
🗣️ 情景例句
The only-child generation brings about many new social problems.
独生子女一代带来了许多新的社会问题。
Let's go to the station to get a train into town.
我们到火车站去乘车进城。
We'll leave some evenings free,that is,if it is all right with you.
如果你们愿意的话，我们想留几个晚上供你们自由支配。