—What’s that unpleasant noise?

—Oh, the road before the main gate          .

A．is repairing

B．is being repaired

C．is repaired

D．has been repaired

新石英砂需用（）浸泡处理后，才供离子交换器使用。

A.盐酸溶液

B.硫酸溶液

C.氢氧化钠溶液

D.食盐溶液