X连锁无丙种球蛋白血症是属于()。
A.T细胞缺陷
B.联合免疫缺陷
C.吞噬细胞缺陷
D.补体系统缺陷
E.B细胞缺陷病
参考答案:E
Roads in this mountain area used to be_______; people found it hard to travel here.
A.in poor conditions
B.in the poor condition
C.in poor condition
D.in a poor condition
到图书馆和档案室查找资料进行研究属于调查研究的()方法。
A.观察
B.问卷
C.访谈
D.文献研究