People in industrial countries take in _________as they actually need every day.

A．twice as much protein

B．protein as much twice

C．twice protein as much

D．protein as twice as much

对椎间盘的描述，正确的是()

A．由髓核、纤维环和上、下软骨板构成

B．位于相邻两椎骨间，共23个

C．自第1颈椎至第1腰椎

D．纤维环为围绕椎体的纤维软骨

E．髓核位于纤维环前缘