“美即快感。”由()提出。
参考答案:休谟
I __________ glasses since I was in primary school and I hate them. They make me look
like a bookworm. [ ]
A. have worn
B. have been wearing
C. have been worn
D. was wearing
图中两灯泡L1,L2在盒内的连接方式未知,电源电压为6V.开关闭合后两灯均发光,电流表读数为0.9 A;若把L1取下,L2仍发光,电流表读数变为0.3 A.
(1)L1和L2是并联还是串联的?
(2)取下L1后,5秒内L2消耗多少电能?
(3)L1的电阻多大?