点A(-2,6)与点B关于原点O对称,则点B的坐标为( )。
(2,-6)
孕激素:
A.雌激素B.孕激素C.雄激素D.促卵泡素E.黄体生成素
What the science teacher does and says of great importance to college students.
A.are
B.is
C.were
D.was