能增加肠道对钙磷吸收的是()。
A.降钙素
B.双磷酸盐
C.维生素D及其活性代谢产物
D.氟化物
E.雌激素
参考答案:C
The man who was being followed stopped from time to time ____ he wanted to tie his shoelaces.
A.as if
B.like
C.what
D.as
民族团结的“五个互相”是()。