A:My mother is serious and she never tells stories to me.
B:My mother is strict and she never tells jokes to me.
C:My mother is strict and she never tells stories to me.
如图所示的电路,闭合开关S,灯L1不发光,灯L2发光,电流表无示数,电压表有示数.则电路故障可能是( )
sin420°=____
黑 牙 林 木 亻
示 奉 方 鸟 五
____ ____ ____ ____ ____
通过下列哪种方法可以提高自己的健康水平( )