这个曲面积分，不是同一个向量场。

OK, and that surface integral, well, it's not for the same vector field.

youdao

了解这两种表述后，我们不仅需要向量场，就是左边这里，这是曲线c上的线积分，向量场在曲线上有定义。

So, in both cases, we need the vector field to be defined not only, I mean, the left hand side makes sense if a vector field is just defined on the curve because it's just a line integral on c.

youdao

一个保守的向量场就是说,沿任意闭曲线的线积分的结果是。

So, to say that a vector field with conservative means 0 that the line integral is zero along any closed curve.

youdao