It took several hundred years ______ paper-making spread to western countries.
| A．when | B．before | C．after | D．since |
31. Stronger and more lasting memories are likely to be formed ________a person is relaxed.
| A．where | B．unless | C．when | D．Although |
30. British scientists said teenagers are programmed to take risks because they enjoy the thrill of dangerous situations________ others.
| A．more than | B．less than | C．other than | D．rather than |
29.Everyone wants to live in a beautiful, comfortable and “livable ” place, but not ________ know where it is.
| A．some | B．either | C．all | D．Both |
28.The comedy Tooth Fairy is based on the story all western children know: If a kid leaves a tooth under their pillow, they’ll receive a visit from the tooth fairy, who takes the tooth and leaves a gift ________.
| A．in general | B．in exchange | C．in total | D．in common |
27. Nearly four hundred supermarkets in Beijing are preparing to dim their lights ________ the "Earth Hour 2010" on Saturday night.
| A．honor | B．honoring | C．to honor | D．having honored |