The school _____you visited yesterday is the place ____I once learned .

A．where; that

B．where; where

C．which; where

D．that; which

无菌罐在什么时候给灌装机生产信号（）

A.无菌罐已经升好温

B.杀菌机供料后无菌罐液位到达设定值

C.无菌罐进行排空填充管路无罐空信号可给灌装机生产信号