如图所示，M为电动机，N为电炉子，电炉子的电阻R=4Ω，电动机的内阻r=1Ω，恒定电压U=12V．当S1闭合、S2断开时，电流表A示数为I1；当S1、S2同时闭合时，电流表A示数为I2=5A；求：
A: Hi, Linda, ____
B: Hi, Mary! Happy birthday! Here is a present for you.
A: Oh, it's very nice of you. ____
B: Guess (猜).
A: Is it a new schoolbag?
B: ____ Open (打开) it and you will see.
A: Wow！ A blue skirt.
B: ____
A: Yes, I love it. Thank you so much.
A. Yes, it is.
B. What is it?
C. No, it isn't.
D. Do you like it?
E. You're welcome.
F. Where do you want to go?
G. Welcome to my birthday party.
