“You look like you're about to nod off.”
You're riding home from a concert with a friend. She looks really sleepy. You say this.
You look like you're about to nod off.
"You're about to ___" means "You're going to ___ soon". Here are some examples with "about to":
I'm about to lose my temper with you.
It looks like they're about to begin. Why don't we go find a seat.
Oh, hi Charles. I was just about to call you.
To "nod off" means to start to go to sleep when you're supposed to be awake.
Here are some situations that you might "nod off" in:
- You're watching a movie late at night.
- You're listening to someone tell a long, boring story.
- You're driving on the highway. (Watch out! This is dangerous!)