Here are some useful expressions for when you are making a presentation or talk, perhaps in a meeting or in a congress or perhaps more informally in a discussion around the coffee machine. Or, if you work at Google, over the table football or going down the slide 

Are there any questions?

That is all I have to say. Are there any questions? 

That’s a good question.  This is a good way of giving yourself time to think.

That’s a good question. Let me think about it for a moment.

As I said earlier, ..….

As I said earlier, we are looking at several different solutions.

I’m afraid I can’t answer that.

I’m afraid I can’t answer that. That information is still confidential.

I’m afraid I don’t know.

That’s a good question. I’m afraid I don’t know the answer. We are still investigating.

I’m not in a position to answer that.  This is a great way of ‘blocking’ questions.

I’m not in a position to answer that.  You will have to ask Peter about that.