We were just about to enter the room.
It's about to rain.
I was just about to leave the house when the telephone rang.
I was about to leave when you telephoned.
I'm about to leave.
Had they known what was about to happen, they would have changed their plans.
What I'm about to say is strictly between you and me.
I was about to go out when the phone rang.
The plane was about to take off when I heard a strange sound.
Your telegram arrived just as I was about to telephone you.