It is pretty well understood _______ controls the flow of carbon dioxide in and out the atmosphere today.
Nearby were two canoes ____ they had come to the island.
Jack is pleased with ____ you have given him and all ____ you have told him.
Do you work near the building ____ colour is yellow?
In the dark street, there wasn’t a single person ____ she could turn for help.
Is this school ____ we visited three years ago?