18. It's cold and the temperature is ______ zero during the night.

17. Thanks ______ your help, I finished the work before dark.

16. Please meet your uncle ______ noon ______ Saturday.

15. You must learn these words ______ heart, and answer my question______ English.

14. The teacher told us the moon travels ______ the earth.

13. Don't read ______ the sun. It's bad ______ your eyes.

12. It's very kind ______ you to help me ______ my maths.

11. -How do you usually come to school, every day?

-Sometimes ______ bike, sometimes ______ foot.

10. Do the twins look ______ their father?

9. Don't laugh ______ others’ mistakes.