Expressing surprise or shock:
* ...he had seen a ghost.
* ...he couldn't believe his ears.
* ...he had been struck speechless.
* ...he had just won the lottery.
Expressing hunger or thirst:
* ...he hadn't eaten in days.
* ...he had been lost in the desert for weeks.
* ...he could smell the delicious aroma of food.
Expressing despair or sadness:
* ...he was about to cry.
* ...he had lost all hope.
* ...he had nothing left to say.
Expressing anger or frustration:
* ...he was about to scream.
* ...he was ready to fight.
* ...he wanted to lash out.
Expressing something else:
* ...he was about to sing.
* ...he was going to tell a joke.
* ...he wanted to ask a question.
The best way to complete the sentence depends on the context and the story you want to tell.