________her home, Mary helps her mother with some housework.

Do you know a spaceship flies at about nineteen kilometers ________ second?

Carl, why not go and help your sister water the flowers there? —Why__________? I’m busy myself. Jack is lying on the grass doing nothing.

Do you know ______ girl who is standing under ____ tree?— Of course! She is Lucy, my classmates.

______ is it from here to your school?—It is about an hour’s walk.[ ]