Hypoellipticity
次椭圆性
🗣️ 情景例句
Maybe I should.
也许我该这样。
Every man has his hobby-horse.
人各有所好。
One day, the man downstairs went to talk to the man. He went upstairs and knocked the door.
一天，楼下人去找楼上人谈谈。 他上楼敲门。