用显微镜观察黑藻细胞的叶绿体,由低倍镜转换成高倍镜,视野亮度和视野内的细胞数目的变化是:[ ]
A.变亮、增多
B.变暗、减少
C.变亮、减少
D.变暗、增多
答案:B
心肌梗死导致心源性休克,梗死面积应 ()
A.大于10%
B.大于20%
C.大于30%
D.大于40%
E.大于25%
-- you interrupt now? Can’t you see I’m on the phone?
--Sorry sir, but it’s urgent.
A.Can
B.Should
C.Must
D.Would