left hand side短语⁴⁸²¹¹ 基本例句 n.左手边 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. 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。163