[单项选择]

Text 4
The scourge that’s plaguing cruise lines--and causing thousands of tourists to rethink their holiday travel plans--didn’t start this year, nor did it even start on a ship. It began, as far as the Centers for Disease Control (CDC) can tell, in Norwalk, U. S., in October 1968, when 116 elementary school children and teachers suddenly became iii. The CDC investigated, and the cause was discovered to be a small, spherical, previously unclassified virus that scientists named, appropriately enough, the Norwalk virus.
Flash forward 34 years, and Norwalk-like viruses ( there’s a whole family of them) are all over the news as one ocean liner after another limps into port with passengers complaining of nausea and vomiting. The CDC, which gets called in whenever more than 2% of a vessel’s passengers come down with the same disease, identified Norwalk as the infectious agent and oversaw thorough ship cleaning--which, to the dismay of the
A. students are easily attacked by the Norwalk-like virus.
B. Norwalk-like viruses tend to break out in closed crowded place.
C. Norwalk-like viruses might cause flu.
D. Norwalk-like viruses are not widespread.

最新试题

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