The sentence structure(结构)of “He often makes me happy” is ________.
--- is your home from school? --- It takes 5 minutes to walk there.
--- Mum, Can I play the game for a moment? --- No, you have finished your homework.
--- Is Mr. Smith in his office now? --- No, he there. I saw him in the library a minute ago.
--- Nancy, apple on the table is for you. --- Thanks. An apple a day keeps the doctor away.
_______ you study harder, you’ll fall behind others. A. If B. Unless C. Until