当然是are或者 were 。首先，be动词指的是在主系表结构中，充当系动词的词语，主要有am， was，were这五种形式。 因为 they是复数形式，它做主语时，如果叫子是现在时be动词就用are， 如果是过去式就用were。
例如
They are students.
They were friends.
they 的be 动词一般现在式时是are，they are friends.一般过去式是were，they were basketball players ten years ago.完成式时是been，they have been retired for ten years.
They的be动词是are或were。
1、用are造句如下：
They are one of this year's hot new bands.
2、用were造句如下：
It's a good job you were there to help.
