Only teachers are permitted to enter the reading room, that is to say, the reading room is only________ to teachers.

 My interest in surfing on the Internet has_______ most of my spare time, but it has repaid me a great deal of enjoyment.

Computer power now allows automatic searches of fingerprint files to match a print at a crime ________.

--- How can I use iPhone 4s?--- Just refer to the _________.

 The scientist knew nothing about the matter, because he was always _________ himself in his study.