巨幼细胞贫血主要为红细胞数减少，红细胞体积缩小。
参考答案：对
—Could you look after your sister, Tina?
—Sorry, mum. I______ my homework now. [ ]
A. am doing
B. will do
C. was doing
D. have done
血小板聚集必须有哪项物质参与 （）
A.血小板GPⅡb/Ⅲa
B.FXⅢ
C.PF3
D.PF4
E.TXA2
