_____his timely help , Kate overcame the hardship at last.                                                                                                                                                                                                                                                                                                                                                                                                                         

A．For

B．Thanks to

C．As a result

D．Because

关于Ham试验的论述，正确的是（）

A.试验中需要用O型血清

B.试验中需要用患者同型或O型红细胞

C.血清酸化后，试管不必加塞

D.患者如有多次输血史，Ham试验可为阴性

E.阳性提示PNH，但确诊，必须做蔗糖溶血试验