人民英雄纪念碑相对天安门是 ____的.(选填“静止”或“运动”)
_________to nuclear radiation, even for a short time, may produce variants of genes in human bodies.
一台理想变压器,原、副线圈的匝数比n1∶n2= 1∶4。原线圈接入220V交流电压,副线圈的电压为( )