()的作用是直接支撑楞式托撑的受压杆件。 ["可调托撑","底座","垫板","立杆"]
桁架梁的高度宜为桁架跨越的()。 ["1/4~1/6","1/2~1/4","1/3~1/5","1/6~1/8"]
桥梁各孔净跨度的综合称为()。 ["A、桥孔总长","B、桥梁长度","C、桥梁全长","D、梁的全长"]
脚手架或操作平台上临时堆放的模板不宜超过()。 ["1层","2层","3层","4层"]
单排扣件式钢管脚手架用于砌筑工程搭设中,操作层小横杆间距应≤()mm。 ["600","1000","1500","1200"]
甲烷的液化温度为零下()℃氢的液化温度为零下()℃氦的液化温度为零下()℃。