小明和小丽在研究：“导体中电流与导体两端电压的关系”时，除了电源（3V）、开关、导线、电流表、电压表、滑动变阻器外，还有可供选择的（A）定值电阻和（B）小灯 泡．

阅读理解

Chen Jie: Which season do you like best, Mike?

Mike: I like summer best.

Chen Jie: Why do you like summer?

Mike: Because I can eat ice-cream and swim in the lake.

Chen Jie: I don't like summer. It's too hot.

Zhang Peng: What's your favourite season?

Chen Jie: Spring. It's sunny and warm. I can plant trees and fly kites. How about you, Zhang Peng?

Zhang Peng: My favourite season is winter.

Mike: Why do you like it?

Zhang Peng: Because I can skate and make a snowman. I like snow.