—Math is too difficult. I want to give it up. —Please don’t. Nothing is _________if you put your heart into it.
--- Help yourself to some more soup. --- .
--- Would you like me to help you? --- .
--- Where’s Bob? --- He_____ to the library.
--- Mary doesn’t remember when and where she this skirt.
- --What's your brother? - --He's a teacher. He art at a school。