仓库的电源开关应安装在库内，以保证库内不工作时库内不充电。单极开关应装在相线上，不得装在零线上。( )
参考答案：错
The development of the internet over the past 20 years has not only changed the way most people live their lives, but also provided a plethora of new platforms for business. The advertising industry adopt the micro blog as a ______ tool, which is a pertinent example.
A．availability B．promotionalC．encryption D．payment
在销售过程中，可以用内燃机油或齿轮油来代替液压油。（）
