单项选择题 Just last week, for example, the World Health Organization (WHO) announced the disturbing disclosure that SARS may be pretty deadlier than previously believed（）.

单项选择题 During many sectors are foundering, the $ 21 billion videogame-software industry is booming, adding game developers at a rate of 2,500 a year in the United States alone（）.

单项选择题 I can still vividly remember to pick our steps in the mountain down the deep valley on my 21st birthday（）.