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A young lady, who seemed to be in her early twenties, received us at the gate and led us to where the seminar was taking place/ being held. We apologized for being late. She smiled, showed us our seats and left. We sat quietly, trying not to cause discomfort to the other participants. The moderator was already halfway through his speech and there was complete silence inside the room.

Are there any mistakes?
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A young lady, who seemed to be in her early twenties, received us at the gate and led us to where the seminar was taking place/ being held. We apologized for being late. She smiled, showed us our seats and left. We sat quietly, trying not to disturb cause discomfort to the other participants. The moderator was already halfway through his speech and there was complete silence inside the room.
Comments  
Thanks Optilang.