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on a conference is the most popular phrase on the web.

at a conference 137,500,000 results on the web	on a conference 137,800,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
In July 1998, 83 countries agreed to the establishment of an international court at a conference sponsored by the United Nations in Rome. I thought you were at a conference. No, I was at a conference in Virginia. Sorry. Professor Whistler is at a conference. He approached me at a conference years ago, asked all sorts of questions about abnormals in ancient mythology. Well, I met him five years ago at a conference. Tom saw his former employer at a conference. A few months ago, we were presenting at a conference in Singapore.	The accusation was made on a conference in Sarajevo. there are possibilities without end. Amita's out of town on a conference. Some women are friendly, some are friendly in hotel rooms while you claim to be on a conference. I've just been enjoying some me time since Max has been away on a conference. Whether you are on a conference, a public event, in vacation, with your car Where you met her on a conference or you see her in other time things Put the war conference room at the Pentagon... and General Bogan in Omaha on a conference line with me.

at a conference

137,500,000 results on the web

on a conference

137,800,000 results on the web

More popular!

In July 1998, 83 countries agreed to the establishment of an international court at a conference sponsored by the United Nations in Rome.
I thought you were at a conference.
No, I was at a conference in Virginia.
Sorry. Professor Whistler is at a conference.
He approached me at a conference years ago, asked all sorts of questions about abnormals in ancient mythology.
Well, I met him five years ago at a conference.
Tom saw his former employer at a conference.
A few months ago, we were presenting at a conference in Singapore.

The accusation was made on a conference in Sarajevo.
there are possibilities without end.
Amita's out of town on a conference.
Some women are friendly, some are friendly in hotel rooms while you claim to be on a conference.
I've just been enjoying some me time since Max has been away on a conference.
Whether you are on a conference, a public event, in vacation, with your car
Where you met her on a conference or you see her in other time things
Put the war conference room at the Pentagon... and General Bogan in Omaha on a conference line with me.