A recent study showed how the temperature, ____ water freezes, can be changed using electric charges. [ ]

A. at which

B. for which

C. in which

D. with which

预防佝偻病应特别强调的是

A．多吃含维生素D的食物

B．经常晒太阳

C．经常口服鱼肝油

D．经常口服钙片

E．合理喂养