请简述以“从泵到泵”方式工作的输油系统特点。
参考答案：各泵站的排量必然相等；各泵站的进出口压力相互直接影响。
Were _____ born in September, 2000? [ ]
A. your mother
B. them
C. they
ZXDSL 531B无线局域网络频率是（）。
A.1.8GHz
B.2.0GHz
C.2.4GHz
D.2.8GHz
