Or perhaps, you could be trying to explain that you don't know whether you can do something or not by a certain date.

又或者，你正在试图解释你没法确定你是否能在一个指定日期前做完某件事。

I don't know 课堂 - SpeakingMax英语口语达人

But we obviously can't commit before we find out whether she's free.

但在确定她是否有时间之前，我们肯定没法确定。

Let me 实战 - SpeakingMax英语口语达人