Doctors are doing research to find out what happens physically when people ______ smoking.

.Look at the beautiful woman, she teaches _____ English very well. She always makes her English classes ________.

Do you know the boy _____ father is a bus driver?—Yes, he is my friend.[ ]

What time does Lucy go to bed every evening?—________.[ ]

．I really don’t know _______I kept the secret papers．