---Are the Smiths living in the house alone ?--- Yes, although they have three sons, _____ of them live with their parents.
Let him _________. Don’t make him __________.
_________ the animals _________ our duty.
We are making a plan _________ water clean.
Let’s _________ what we can do to save the animals in danger.
--- How can you _________ there? --- ___________air.