______in the past, at the moment it is a favorite choice for wedding gown.

A. Unpopular has as white been

B. White has been as unpopular
C. Unpopular has been as white

D. Unpopular as white has been

如图，是居民楼墙外用铁三角架搁放空调主机的示意图，要使铁架较为牢固、安全。应把主机放在A处还是B处？请你在选择的主机上画出它的重力示意图和重力对O点的力臂。