___________, Mother will wait for him to have dinner together.

A．However late is he

B．However he is late

C．However is he late

D．However late he is

以下关于双缩脲法测定总蛋白的错误说法是（）

A.蛋白质的肽键与反应试剂形成络合物

B.双缩脲法是首选的常规方法

C.双缩脲法的优点是操作简单，重复性好

D.反应是在酸性溶液中进行的

E.反应中产生紫红色络合物