it is/was the first time +that+clause中从句用什么时态?

it is/was the first time +that+clause中从句用什么时态?
it is/was the first time +that+clause中从句用什么时态?

it is/was the first time +that+clause中从句用什么时态?
It is the first time+定从的句子(从句用现在完成时）
It was the first time+定从的句(从句用过去完成时

it is the first time +that+clause 前面用一般现在时，后面也用一般现在时。
it was the first time +that+clause 前面用一般过去时，后面也用一般过去时。