国家助学贷款管理办法规定借款人必须在毕业后（）年内还清。
A.2
B.4
C.6
D.10
参考答案：C
A. But where's your raincoat? B. It's in my bag, on the bike. C. Yes , dear. D. The desk near the window? E. Where are my shoes,Mum?
HAV是（）
A.呼吸道病毒
B.RNA病毒
C.DNA病毒
D.逆转录病毒
E.肿瘤病毒
