Before starting a reciprocating, steam-driven pump that has been idle for a period of time, you should （）. ["open the steam line mot valve","drain the steam cylinder","close the steam cylinder drains","open the liquid cylinder drai"]
微笑的主要特征是什么？
在Excel中，对单元格输入数据后，（）。 ["文字左对齐，数字右对齐","文字右对齐，数字右对齐","文字左对齐，数字左对齐","文字右对齐，数字左对齐"]
服务人员注视的角度主要有什么？
When air becomes trapped in the hydraulic fluid of a steering system, the （）. ["rudder will respond sluggishly","hydraulic rams will over-speed","sight glass will show bubbles","ram relief valves will lift"]
植物叶片中合成的有机物是以什么形式和通过什么途径运输到根部？如何用实验证明植物体内有机运输的形式和途径？
