会话急救包：

I'm not sure about that.我想不大可行吧。

I wouldn't say that.我不赞成。

I 'm not sure that the case.我不确定是否是那样。

Why not?为什么不?

It may not be that simple.问题可能没那么简单。

I don't often use them.我很少使用。

I Wouldn't really know.我不知道。

I 'm not really sure.我不大不确定。

I wouldn't know anything about that.我不知道。

There is nothing wrong with that.那个没有什么不好。