各种杆件距轨底的净距离不大于（）。
A.10mm
B.5mm
C.15mm
D.20mm
参考答案：A
1 want to _____ a magazine because I like writing articles. [ ]
A. work at
B. work on
C. work for
D. work as
大跨度、在低温下承受动荷载和冲击荷载的结构物中应选用（）钢材。
A．Q345-A
B．Q345-B
C．Q345-C
D．Q345-E
