下面是我们熟悉的物质,其中属于纯净物的是 [ ]
A．空气
B．氮气
C．食醋
D．牛奶
答案：B
The project________by the end of 2011 will expand the city's cable TV network to cover more users. [ ]
A. being accomplished
B. accomplished
C. to be accomplished
D. having been accomplished
磺胺嘧啶银主要用于治疗（）
A.流脑
B.尿路感染
C.创伤面感染
D.呼吸道感染
E.肠道感染
