题干
-- Miss Wang, I'm sorry I am late because I _______ to catch the early bus.
-- It doesn't matter. You'd better come to school earlier next time.
A：needed
B：failed
C：managed
答案(点此获取答案解析）
B
标有“220V 100W”的甲灯和标有“220V 200W”的乙灯串联在家庭电路中，比较两个灯泡的亮度