三焦的募穴是（）
A.中极
B.石门
C.京门
D.章门
E.天枢
参考答案：B
30. The No. 5 subway line, ______in October, 2007, has greatly improved the traffic conditions in Beijing.
A．opened
B．was opened
C．being opened
D．to be opened
WQ-5A型万用电桥主要由哪些部分组成？
