Before you open the floor to questions you could say,
'Thank you all for listening, now I'd love to hear from you - who would like to ask the first question?'
This gives the audience the signal that you are done 'giving' and are ready to 'receive'. They can then jump in and ask away.
- (Thanks for listening) .... Now I’d like to invite your comments.
- Now we have time for questions and discussion.
- Right. Now, any questions or comments?