单项填空
1.抓住题目的关键词
1) The line was busy; someone _________
       the phone.
     A. may be busy            B. may have used
     C. must have been using   D. must be using

2) ----Do you feel like ______ in bed on Sundays?
        ----Yes, but I’m always too busy _____ so.
     A. to lie; doing          B. lie; doing
     C. lying; doing           D. lying; to do