His lectures are terribly boring.
Being bored, the audience began to yawn.
You should have seen yourself, yawning all through the meeting.
Every time I looked at him, he was yawning.
They were all so tired that they could do nothing but yawn.
We yawn when sleepy or bored.
Cover your mouth when you cough, sneeze, or yawn.
We yawn when we are short of oxygen.