Poid
形心(曲线), 拟正弦线, 膺正弦线, 瞬心轨迹
🗣️ 情景例句
I don't know what-to do.
我不知道怎么做。
In secondary school, children study history and geography.
中学的小孩会读历史和地理。
They will be trying to keep order.
他们将设法维持秩序。