英语连词前面的逗号有什么用?.,and.

英语连词前面的逗号有什么用?.,and.
举个例子：
1 Children will play with dolls equipped with personality chips,computers with in-built personalities will be regarded as workmates rather than tools,relaxation will be in front of smell-television,and digital age will have arrived.
2.In Europe,as elsewhere,multi-media groups have been increasingly successful:groups which bring together television,radio newspapers,magazines and publishing houses that work in relation to one another.
1.中的.......and digital 中的magazines and publishing 有什么区别？和区别的窍门？

并列句子时为“A,and B” ,I like to play,and she like to eat