According to the passage, scientists have discovered that influenza viruses_____.
举一反三
- According to the passage, scientists have discovered that influenza viruses ______ . A: cause ill health in wild birds B: do not always cause symptoms in birds C: are rarely present in wild birds D: change when transferred from animals to man
- It can be inferred from the passage that all of the following are with of producing new strains of influenza viruses except ______ . A: two influenza viruses in the same animal recombining B: animal viruses recombining with human viruses C: two animal viruses recombining in one animal D: two animal viruses recombining in a human
- It can be inferred from the passage that all of the following are ways of producing new strains of influenza viruses EXCEPT _____.
- According to the passage, a great variety of influenza strains can appear when_____.
- By the year 2010, scientists probably ______ an effective treatment for cancer. A: will have discovered B: are discovering C: will be discovering D: have discovered