Mark Twain ______ school and began to work at the age of twelve.

Their car broke down while they ________in the desert.

No one ___________ for a drive, because the weather is so bad.

 Each year quite a lot of food ______ around the world. It’s really time for us to do something.

—Where have you _________ all day? —I came back at noon and I _________ in this room ever since.