导致血小板输注无效的非免疫性因素是（）。
A.HLA抗体
B.HPA抗体
C.ABO抗体
D.Ig抗体
E.脾大
参考答案：E
She is very dear to us. We have been prepared to do _____ it takes to save her life. [ ]
A. whichever
B. however
C. whatever
D. whoever
正常恒牙具有哪些特征？
