网友描述问题不够规范和准确,而且让人看不太懂。应直接说:“and 之前加不加逗号有什么区别” 。
连词 and 连接并列成分,包括并列分句。如果前面的成分(尤其从句)太长,这时需要停顿一下,口语需要停顿,书面语则加逗号,这便产生了 and 前加逗号。如果前文很短,则不需要停顿,也就不加逗号。比较:
He is a worker and works every day.
He works in a company far away from home,and goes to work by bike every day.