We keep replacing the old ones who die off.
"But now we love them very much, so I just keep replacing their parts when they become damaged."
He tried to take off the oxygen mask but the doctors kept replacing it.
But in the process, I kept replacing the older songs, one song at a time.
Of course, they had to keep replacing this huge population.
He doesn't, but he's so used to having one, he keeps replacing it.
The only problem is, I have to keep replacing the heads.
They held for a while and he had to keep replacing them.
The air keeps replacing itself, more or less, by volcanic action.
As he spoke, sets of musicians kept replacing one another.
