請問一串名詞時，過程中的逗點，何時才要加/不加/可加可不加?
具體的情況:
1. A and B 或者 A or B 這不加逗點
2. A, B and C 或者 A, B or C 不加逗點
還是說也可以加逗點如下?
A, B, and C 或者 A, B, or C
但如果更多名詞連接一起呢? 逗點何時必加
，何時必不加而何時可加可不加呢?
例如以下從書中摘錄的:
1. ... for the purpose of providing medical, surgical, hospital
care, sickness, accident, disability, death, unemployment or
vacation benefits, apprenticeship or other training programs,
day care centers, scholarship funds, prepaid legal services
or severance benefits
2. First, a "savings clause" allows that state laws pertaining to
the "regulation" of insurance, banking, securities, and generally
applicable criminal laws are not preempted.