—_ __ did you eat this morning?
—A sandwich. [ ]
A. How
B. What
C. Why
答案：B
计划免疫
螺栓球节点网架总拼完成后，高强度螺栓与球节点应紧固连接，高强度螺栓拧入螺栓球内的螺纹长度不应小于( )d(d为螺栓直径)。
A．1.5 B．1.3 C．1.2 D．1.0
