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