Mike often got into trouble with others at school,but his teacher didn't ___trying to help him .           [ ]

A worry about  

B afford to  

C give up      

D pay attention to

小明同学用如图所示的实验装置探究“电流通过导体产生的热量与电阻的关系”．

（1）实验中通过观察______来比较电流产生的热量的多少．

（2）为了便于比较两种不同电阻丝通过电流后产生热量的多少，甲、乙两瓶中要装入______、初温度相同的同种液体．

（3）实验结论：在电流和通电时间一定时，______越大产生的热量越多．