五位同学就周末的情况作了记录并拍了照片，请将照片和记录配对。

小题1:I had a great weekend. I went to the beach with my friends and we played volleyball there. It was tiring but fun!

小题2:I went to the beach with my friend John. We lay on the beach. The sun was shining. The sand was comfortable. We came back very late.

小题3:we had a nice time in the mountains. The weather was cool and cloudy. Just great for hiking.

小题4:My weekend wasn’t so good. I went to visit my best friend, but she was not at home. It was raining all day and I was cold and wet.

小题5:I had a great weekend. I visited my aunt. Iplayed with my friends in a swimming pool. It was very hot , but it was relaxing there.

（6分）为了测定电源电动势E、内电阻r的大小并同时描绘出小灯泡的伏安特性曲线，某同学设计了如图甲所示的电路。闭合开关，调节电阻箱的阻值，同时记录电阻箱的阻值R，电压表V₁的示数U₁，电压表V₂的示数U₂。根据记录数据计算出流过电阻箱的电流I，分别描绘了a、b两条U—I图线，如图乙所示。请回答下列问题：

（1）写出流过电阻箱的电流I的表达式I=     ；（用U₁、U₂、R表示）

（2）电源两端电压随电流变化的图象是    （选填“a”或“b”）；当电阻箱阻值调节为   时，两条图线存在交点；

（3）根据图乙可以求得电源的电动势E=   V，内电阻r=   ，该电路中小灯泡消耗的最大功率为   W。（本小题结果均保留两位有效数字）