21. - Do you know the lady over there?

- Oh yes. ______ is my English teacher.

   A. He    B. She    C. His    D. Her

22. My brother always goes to the library ______ Saturday morning.

   A. on    B. in    C. at    D. to

23. She is not good at math, ______ she never gives it up.

   A. or    B. so    C. but    D. and