21. It’s kind __________ you to get a cup of tea for me.
     A. for                    B. to                    C. of                    D. at
22. You should wear white if you are _________________.
    A. tired                   B. strength            C. stressed            D. strong
23. Mum often worries about _____________ enough sleep because she’s getting old.
    A. without having   B. not having        C. don’t have        D. doesn’t have