--Could you tell us __________ ?

--About two weeks.

A．how often are we going to be away

B．how often we are going to be away

C．how long are we going to be away

D．how long we are going to be away

谷类食物与下列哪种食物混合食用，可提高其蛋白质生物价值（）

A.鸡蛋

B.牛奶

C.鱼、虾

D.大豆

E.猪肉