题干
－I didn’t know you were good friends.
－You ______. I have known her since she moved here. You were studying abroad then.
A：may have
B：needn’t have
C：couldn’t have
D：must have
答案(点此获取答案解析）
C
。现将重物向下拉
，然后放手，则在刚释放的瞬间，重物加速度的大小是（
=
）
