But another place where this comes up, if you remember what we did in the plane, curl also came up when we tried to convert line integrals into double integrals.
除了这些，旋度还有一个用处，如果你还记得，我们讨论平面的时候,当把线积分转换成二重积分的时候。
3
The first line of a poem called “Bogland”, for example, came to him as he was putting his right leg into his trousers, he recalls.