The noise from the top floor, loud and constant, of the meetingroom ________ can be clearly heard in our classroom.[ ]

A．being decorated  

B．having been decorated

C．to be decorated  

D．decorated

下列各组物质在水溶液中能够共存，而且加入紫色石蕊试液后显蓝色的是 [ ]

A．KOH、CuSO₄、H₂SO₄

B．NaNO₃、Na₂SO₄、NH₃·H₂O

C．KCl、Ba（NO₃）₂、HCl

D．NH₄NO₃、KOH、K₂SO₄