某机电安装公司承建某造纸厂的大型进口造纸机的安装任务，总重约500 t，零件非常多，共229箱。按照程序进行安装，设备对安装精度要求很高。按照施工技术方案，需要一台100t的起重机。对于造纸机的基础要求有预压。

机械设备安装工程施工及验收规范适用的施工范围是从（）起，到空负荷试运转合格为止。

A．施工准备

B．开箱点件

C．设备运输到现场

D．开箱点件完毕

If C is the temperature in degrees Celsins and F is the temperature in degrees Fahrenheit, then the relationship between temperatures on the two scales is expressed by the equation 9C=5(F-32). On a day when the temperature extremes recorded at a certain weather station differed by 45 degrees on the Fahrenheit scale, by how many degrees did the temperature extremes differ on the Celsius scale ？（）

A．

B．13

C．25

D．45

E．81