被英语里的and前面的逗号整糊涂了,请教英语达人.

问题描述:

被英语里的and前面的逗号整糊涂了,请教英语达人.
第一句话:Being optimistic can enable people to behave wisely,kindly and confidently,and it is crucial for any individual's ,in terms of both character and competence.(,and有个逗号)
第二句话:The title of the movie is The Legend of 1900 and there are some reasons for my recommendation.( and前没逗号)
第三句话:With optimism,the goal we set can be reached ,and the hard nut can be cracked.( ,and前有逗号)
这里的and前的逗号或不加逗号,难道仅仅就是为了看起来简短或整齐吗?有没有语法上的讲究呢?

断句,看的是作者的语气和感情.加不加逗号问题不大.至少语法上 没有对错之分.