Quadric
a. 二次的\\nn. 二次曲面
🗣️ 情景例句
What's the problem?
是什么问题？
The worker is pounding steel pipes to mend the leakage of water.
管道工为了修缮漏水而敲打着下水道的铁管。
As soon as he had hung up, he went over to the workmen and told them that if a policeman ordered them to go away, they were not take him seriously.
挂上电话后，他又马上来到工人那儿，告诉他们若有个警察来让他们走开，不要把他当回事，