All the doctors in the hospital insisted that he________ badly wounded and that he________ at once.

A．should be; be operated on

B．were; must be operated on

C．was; should be operated

D．was; be operated on

在反应A+3B=2C+2D中，A和B的相对分子质量之比为9：11，已知1.8gA与一定量B恰好完全反应，生成5.1gD，则在此反应中B和C的质量比为（　　）

A．2：1

B．3：4

C．12：11

D．1：1