题干
—What has happened to you, Mary? You're so sad.
—My application was once again.
A：turned around
B：turned down
C：turned off
D：turned in
答案(点此获取答案解析）
B
、
为电场中的两点．一个离子从
运动到
（不计重力），轨迹如图所示．则下列判断正确的是