A:1a2-1
B:1a+1
C:1a-1
D:1a2+1
图中电阻箱的示数为____ Ω.
电路连接如图所示,灯泡L上标有“12V 3.6W”字样。闭合开关,灯泡L正常发光,电流表示数为0.2A。求:
在等差数列{an}中,若a3+a4+a5+a6+a7=450,则a2+a8的值等于( )
______ awful day it was that day! We experienced _______ unusual weather in London.