So, one of them says the line integral for the work done by a vector field along a closed curve counterclockwise is equal to the double integral of a curl of a field over the enclosed region.

其中一种说明了，在向量场上，沿逆时针方向，向量做的功等于，平面区域上旋度F的二重积分。

youdao

Of course, you can also do it geometrically because geometrically, you can see in the picture along the X-axis, the vector field is pointing vertically.

当然，你可以直观地算出来是因为，你可以直观地在图上看出x轴上，向量场是垂直指向的。

youdao

Normal vector points up. Imagine that you put your thumb along c, your index towards s and then your middle finger points up.

法向量向上，想象你把你的大拇指沿着C放，食指指向s，那么你的中指就会向上。

youdao

Acquisitions include French media conglomerate Vivendi Universal, which GE folded into its NBC Universal unit, along with diagnostic imaging company Amersham and natural gas systems supplier Vector Gray.

FORBES: GE, At Your Service