加热加酸法使混浊尿液变清，可判断此尿液为（）。

A.脓尿

B.菌尿

C.结晶尿

D.血红蛋白尿

E.胆红素尿

You needn’t have come in person --- a letter _____enough.

A．would be

B．is

C．would have been

D．was