某五层住宅,层高为3.0m,用经验法估算从室外地面算起该给水系统所需的压力为()kPa。
A.28
B.240
C.200
D.250
参考答案:B
Tom was caught when he was cutting trees.
为什么无油螺杆压缩机转子齿顶设有密封齿?