单项选择题
According to the news, the world's highest railway climbs to more than ______.above sea level.
单项选择题 According to the doctor, current ways of controlling bird flu do not include______.
单项选择题 What does the UN report find about the Chernobyl nuclear disaster
单项选择题 According to the news, whether the bird flu will cause a great casualty depends on______.
