单项选择题 在如图所示电路中,已知稳压管DZ1、DZ2的稳定电压分别为6V和7V,且具有理想的稳压特性,可求得输出电压为_________。  A、1V B、6V C、13V D、7V

判断题 As for a piece of 4/4, with its first measure starting with a weak beat, its first measure is two beats and the last, one beat.

单项选择题 苦杏仁可以生服 A、正确 B、错误