Read the sentence.We needed to cross the foaming river to get back to camp, _______ the river had washed the bridge away, _______ all that was left was a few pieces of broken wood.

“But” shows the contrast between needing to cross the river and finding that the bridge was gone. “And” then adds what remained of the bridge: a few pieces of broken wood. So the sentence reads, “...but the river had washed the bridge away, and all that was left was a few pieces of broken wood.”

AI-written and checked against the verified answer.