当你询问对方什么时候写作业时说:A. What are you doing ?B. When do you do homework ?C. Who are you ?
( ) The doctor often tells him __________ more exercise.
( ) You should ___________ your little brother when your mother is out.
( ) Sometimes walking is __________ than driving during the busy traffic time.
( ) My sister was born _____________ a Friday morning.
( ) Mary is a student of___________.