单项选择题
设L是从A(1,0)到B(-1,2)的线段,则曲线积分(x+y)ds等于:()
A.-2 B.2 C.2 D.0
A.(5/3)π B.(5/6)π C.(10/7)π D.(10/11)π
A.0 B.1 C.2/3 D.1/3