—It is       useful book.—Yes, it tells us how to play       football.

This is ____ my pen. I’m writing with ___ pen.

Everyone knows that _____ sun is in the center of the solar system（太阳系）

Is ___ woman in red your mother? –Yes. She is ____ teacher and works in our school.

–It’s       hard work to achieve a balance between schoolwork and hobbies.–So it is, but we have to.