In the UK and the USA people often give flowers and cakes as birthday presents. They ________ open their presents at once.

--- ______ do you play football?　 --- Once a week.

-- Is air the lightest thing in the world?-- Not            . Scientists from Zhejiang University have just developed the world’s lightest material.

---Mr. Bill always makes his class very lively and interesting. --- You are right. No one teaches ____.

Gina's books are   _  --on her bed, on the sofa and under the chair.