When the mother heard a bomb exploded _____ his son was working, her heart _______, wondering if

her son was safe.      [ ]

A. where; sank  

B. in which ; broke  

C. that; was broken    

D. at which; sank

如图所示：若关闭Ⅰ阀，打开Ⅱ阀，让潮湿的氯气经过甲瓶后，通入乙瓶，布条不褪色；若关闭Ⅱ阀打开Ⅰ阀，再通入这种气体，布条褪色。甲瓶中所盛的试剂不可能是

A．浓H₂SO₄

B．NaOH溶液

C．NaCl溶液

D．Ca(OH)₂溶液