I'm afraid I can't give you a definite reply now. 恐怕我现在无法给你一个明确的答复。

I can't make a decision right now. 我现在无法作出决定。

I just need some time to think it over. 我需要时间考虑考虑。

We are still a little unsure about the prospect, though. 不过，我们对于前景还是有点不能确定。

There are certain points that I'll have to consider very carefully. 有些问题我得慎重考虑。

That may well be so. I'm not sure. 很可能是这样的。我不敢确定。

It all depends. 这得看情况而定。