题干
the Internet is , I do not think it is a good idea to spend too much time on it.
A：When; greatly beneficial
B：As; a great benefit
C：While; of great benefit
D：Now; of no benefit
答案(点此获取答案解析）
C
轴正方向的夹角为θ。若空间存在沿y轴负方向的匀强电场，场强大小E=100V/m，则O、p两点的电势差可表示为（ ）