If you feel tired and sick of fat food, that is ______ you have to go to the hospital for medical examination.
—What are you busy ___?—I’m busy ___ a letter to my mother.
There’s somebody walking behind us. I think ___.
The girl devoted all her free time she had __ others.
—Jane, see, what did I find?—Oh, my lost keys! ____.
Jack, it’s __ bad manners to blow your nose at ___ table.