21. China has sent two patrol ships to ______waters near Diaoyu Islands after Japan signed ______ contract to buy the islands.
A. /; a B. the; a C. /; the D. the; the
22. They have demanded to the authorities that all the facts _____ known to the public.
A. must be made B. are made C. be made D. should make
23. The runners _____their positions on the starting line.
A. picked up B. made up C. put up D. took up
