China, a country with 145 million elderly people, will remain _______ ageing society during this century, according to _______ Chinese population experts.

A．/; the

B．an; /

C．an; the

D．the; /

培养病毒所用的细胞为（）

A.原核细胞，真核细胞，传代细胞等

B.真核细胞，传代细胞，二倍体细胞等

C.原代细胞，传代细胞，真核细胞等

D.原代细胞，传代细胞，二倍体细胞等

E.原核细胞，真核细胞，二倍体细胞等