Noticed

I noticed you entering my room.

No one noticed the bear's appearance.

It was there when I noticed it.

He noticed a letter on the desk.

We noticed the man enter her room.

A careful reader would have noticed the mistake.

If I had noticed her, I would have got her autograph.

Holmes went out of the room without being noticed by anyone.

I noticed, among other things, that he was drunk.

Tom noticed a drunkard lying in the street.