做过滤的实验时，玻璃棒的作用是______；易潮解的物质如氢氧化钠固体必须放在______里称量；制取气体之前，必须要先检查装置的______；在点燃可燃性气体之前一定要______；加热氯酸钾、二氧化锰混合物制氧气，用排水法收集氧气，在实验结束时，必须先把______，然后再______．

He said_________ he would visit me and______ he would bring a special present to me.[ ]

A. \, \

B. that, \

C. \, that

D. that, what