方向(d)和()为曲面上P点处的两个主方向,那么( )

A、(d)和(<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/15129794141076544e80134874ffb9af5fc9d77547e9f.png" alt="上传图片">)正交

B、(d)和(<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/151297941538490fa216c0bba4f0e99fcec71fb463c70.png" alt="上传图片">)共轭

C、d)和(<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/1512979416583675c0177ae6c4b69a8f288f64b1e3af6.png" alt="上传图片">)平行

D、d和(<img src="https://s3.cn-north-1.amazonaws.com.cn/qingshuxuetang/examination/imgUplod/1512979417550d76f12e58f7f44dc9efd9ee30cc52e54.png" alt="上传图片">)方向相反