如图是机场的安检人员用手持金属探测器检查乘客的情景，当探测线圈靠近金属物体时，在金属物体中就会产生电流，如果能检测出这种变化，就可以判定探测线圈下面有金属物体了。图中能反映出金属探测器工作原理的是（  ）

补全对话(选择)。

A: Can I help you?

B: Yes, please.____

A: For your daughter? Look, the shoes are really nice. Do you like them?

B: Yes. But I'm afraid my daughter doesn't like the color.____

A: Sure. There are different kinds of shoes over there. What color does she like?

B:____ And black is her favorite.

A: What size does she need?

B: Size 9. Let me see. Um, this pair of shoes looks nice. They are OK with her.____

A: They are only 99 yuan.

B:____ Here is the money. Thanks a lot.

A: You are welcome.

 A. I'll take them.

 B. Can you go to other shops?

 C. I'm sorry about it.

 D. May I have a look at the other shoes?

 E. How much are they?

 F. I need a pair of shoes for my daughter.

 G. She likes white and black.

青少年正是长身体的时期，饮食既要均衡、适量，又要注意卫生、安全，下列说法正确的是（  ）