21. ______ important thing in life is to have a great aim, and ______ determination to attain it.
A. An ; 不填 B. A ; the C. The ; the D. The ; 不填
22. I have no one ____ me, for I can deal with it all by myself.
A. to help B. to have helped C. help D. helped
23. We are in a difficult position in____ we have nobody properly qualified for this work.
A. that B. when C. what D. where
