21. Alan had _____ e-dictionary, which plays _____ important part in his study.
A. a, a B. an, an C. the, an D.不填, a
22. Albert is very _____ and has never paid the bill when we have meals together.
A. active B. selfless C. warm-hearted D. mean
23.—Are you free tomorrow afternoon, David?
—I’m afraid not. My parents and I ______ my uncle’s family in the countryside.
A. are visiting B. visit C. visited D. have visited
