可以出现2个and,也可以多个,并列时,也可以只在最后两个之间加and.
He has two books, and one ruler, and two pencils.
=He has two books, one ruler and two pencils.
I have two soccer balls, three volleyballs, four basketballs and five baseballs and bats.
这是一个句子.这样写可以.因为最后的and连接的是baseballs和bats,即棒球和打棒球用的球棒.第一个and是连接所有并列的部分,此处吧baseballs and bats看成了一个整体和前面的并列.