铁路简支梁主要分为板式梁、T形梁和()。
A.箱梁
B.混凝土梁
C.钢梁
D.异型梁
参考答案：A
_ we left the building that I realized how dangerous the situation had been.
A．Only then
B．It was only then
C．Only after
D．It was only after
有维系联络全身阳经作用的是（）
A.阴维脉
B.阳维脉
C.跷脉
D.督脉
E.冲脉
