【简答题】People in Norway are the happiest in the world. That finding comes from a report which came out this week. It shows Norwegians are happier than people int over 150 countries. The 2017 Word Happiness R...

【单选题】梯子的最高()层不允许站立作业

【多选题】梯子按材质分为：（）

【简答题】It was Saturday yesterday. I had no lessons. I got up at six. After breakfast，I went to a farm by truck(卡车) with my classmates to help the farmers with apple harvest(收获). As soon as we went there, we ...

【简答题】梯子不够高度时（）用。

【单选题】金属梯子不适于以下什么工作场所（）

【单选题】金属梯子不适于以下什么工作场所 ?

【判断题】吊篮作业人员不得穿着硬底鞋、塑料底鞋、拖鞋或其它易滑的鞋子进作业，作业时经批准可以在悬吊平台内使用梯子、凳子、搁板等攀高工具和在悬吊平台外另设吊具进行作业。

【单选题】甲、乙、丙三个梯子斜靠在同一堵墙上（梯子顶端靠墙），小明测得甲与地面的夹角为60°；乙的底端距离墙脚移米，顶端距离墙脚3米；丙的坡度为，那么这三个梯子的倾斜程度是 [ ]

【单选题】梯子的底宽不得小于（）CM。