肾脏分泌肾素的部位是（）
A.球旁细胞
B.间质细胞
C.致密斑
D.肾小球细胞
E.肾小管上皮细胞
参考答案：A
— What would you do _____ the lost library book?
— I would try to find it or pay _____ it. [ ]
A. about, for
B. for, to
C. with, to
D. with, for
碳溶于a-Fe中的固溶体叫（）
A.铁素体
B.奥氏体
C.渗碳体
