21. In India more than one hundred languages are spoken， ________ which only fourteen are recognized as official.
A) of B) in C) with D) within
22. Techniques for ________ sleep would involve learning to control both mind and body so that sleep can occur.
A) cultivating B) promoting C) pushing D) strengthening
23. It is important to ___ between the rules of grammar and the conventions of written language.
A) determine B) identify C) explore D) distinguish
24. It is too early to say whether IBM‘s competitors will be able to ________ their products to the new hardware at an affordable cost.
A) adapt B) stick C) yield D) adopt
25. This research has attracted wide coverage in the ________ and has featured on BBC television‘s Tomorrow’s World.
A) data B) source C) message D) media
21-25 ABDAD