英语六级考试精编阅读理解练习题(2)

　　47.If the drug proves effective in human trials，it could enhance the effectiveness of existing AIDS drugs in___________________.

　　48.What has become standard cocktail therapy?

　　49.While integrase deletes an immune cells genetic material and replaces it with its own，it acts like_____________in a word processor.

　　50.Why would anti-AIDS drugs stop working?

　　51.According to Steven Young，if scientists get the data that_______，they would petition for fast track status.