31._____for a strong and fair climate agreement at the key UN summit in Copenhagen, 50,000 people in London wore blue and went to the streets.

A．Call

B．Calling

C．To call

D．Called

Armp公理系统中有一条推理规则为：若X→Y为F所逻辑蕴涵，且Z

U，则XZ→YZ为F所逻辑蕴涵。这条推理规则称作______。