小明同学按照如图所示的电路“研究串联电路中电流、电压的特点”,当开关闭合时,灯L1亮,灯L2不亮,电流表和电压表均有示数.则故障原因可能是
A:L1断路
B:L1短路
C:L2断路
D:L2短路
有关我国河流的叙述,正确的是( )
— Are you Tom likes basketball?
— Yes. He always plays basketball after school.
计算:cos245°=____.