A:①③
B:②③
C:①②
D:③④
Mum:Mary. ____
Mary:It's very pretty.
Assistant: ____
Mum:Yes. ____
Assistant:It's $ 99.
Mum:Oh, that's expensive.
Assistant:Do you like that blue skirt?
Mary:Yes. ____
Mum:OK. How much is it?
Assistant:It's $ 50.
Mum: ____
A. Can I help you?
B. OK. I'll take it.
C. How do you like this dress?
D. I like blue.
E. How much is it?
如图所示,R1=25Ω,小灯泡L的规格为“2.5V 0.3A”,电源电压保持不变.
①S1、S2都断开时,小灯泡L正常发光,求电源电压;
②S1、S2都闭合时,电流表示数变为0.6A,求R2的阻值.
写出近义词
空—____ 悲—____