在两个主要子句之间使用逗号，这两个子句用and或者or分隔。

Example: We ran out of fuel, and the nearest petrol station was 5 miles away.

使用逗号分隔序列中句子的各个部分。

Example: She ran down the stairs, opened the door, saw her boyfriend(,) and gave him a kiss.

如果句子的这些部分被and或or分隔，请不要使用逗号。

Example: She ran down the stairs and opened the door and saw her boyfriend and gave him a kiss.