煤气管道每()m间距应设置一个排水器。
A.500
B.200~25O
C.300
D.600
参考答案:B
______ you come across some new words, don’t refer to your dictionary at once but guess their meanings according to the context.
A.Every time
B.The first time
C.Now that
D.If only
“公作”、“分地”