帮我翻译一下：这些人是我的堂兄弟，那些人是我的朋友

都可以。\也可以都不用，汉译英，不要逐字逐句翻译。会不符合英语习惯的
These are my cousins and those are my friends.

这个句子应该是这样地~~these are my brothers,and those are my friends.
these和those是代词，本身就有代替人或物品的意思，加上person就重复了。

都可以表示人，person复数形式应加s，people是集合名词，不能加s.
These people are my cousins,those are my friends.

These people are my cousins, those people are my friends.
单数用person，复数用people

These people are my cousin ,while those are my friends

these are my cousins and those are my friends