第6部分：完形填空
阅读下面的短文，文中有15处空白，每处空白给出了4个选项，请根据短文的内容从4个选项中选择1个最佳答案。
Influenza
Influenza has been with us a long time．According___1_____ some Greek writers on medical history，the outbreak of 412 B.C．was of influenza．The same has been suggested of the sickness that swept through l the Greek army_____2_____ Syracuse in 395 B．C． Flu is a disease that moves most quickly among people____3____ in crowded conditions，hence，it is likely to attack armies．
During the nineteenth century there were five widespread＿＿4＿＿ of influenza．The last of the five_____5_____ in l889 and marked the beginning of the story of influenza in our time．Like the_____6_____started in Asia．
For more than forty years before that outbreak，influenza had steadily＿＿7＿＿ and was believed to be dying out.2 A new group of outbreaks was introduced by the great outbreak of l889-1890 and for the next quarter of a century flu ____8____ a constant threat．
In April 1918 flu broke out3 among American troops stationed in France．
It quickly spread through all the armies but caused relatively____9____deaths．Four months later，____10____，a second outbreak started which proved to be a killer. It killed not only the old and already sick but also____11_____young adults．It went through4 every country in the world，only a few distant islands in the South Atlantic and the Pacific remaining____12 ____．It brought the life of whole countries_____13____，food supplies stopped and work loss was very great．Before the great outbreak ended，it___14___ at least l5 million people．Thereafter there have been several great outbreaks throughout the world．It is thus____15_____ that influenza is a terrible infection that we have to pay more attention to.
