that时态，now

now that可用于多种时态。

Now that you mention it ， she did seem to be in a strange mood.

既然你说到这事儿，她确实好像情绪不大对。

Now that you mention it ， i do remember .你这样一说，我想起来了。

He knew now that he was wasting his time .他现在明白自己是在白废口舌了。

Now that you are here ， you 'd better stay .既然你已经来了，最好还是住下。

You understand now that i command ?现在我作主，你明白了吗