GWD21-21

shunliqumeiguo

21. GWD21-Q21:
Which of the following most logically completes the passage?

Mastitis is an infection of the udder in cows that, although not dangerous, causes them to give poor-quality milk.  Most cases of mastitis are caused by the bacterium Staphylococcus aureus, against which antibiotics are ineffective.  However, a related bacterium, Staphylococcus simulans, quickly clears up even severe infections of S. aureus simply by displacing the bacteria.  S. simulans is nevertheless unlikely to become the preferred treatment for cases of mastitis, since ______.
A.    certain dangerous bacteria that normally cannot take hold can do so in the presence of S. simulans
B.    the current resistance of S. aureus to antibiotics derives in part from a past pattern of overuse of those antibiotics
C.    the milk from cows infected with S. aureus is generally not of such poor quality as to be entirely unusable
D.    careful farming practice can reduce the incidence of mastitis to a minimum
E.    the only symptom of mild cases of mastitis is the deterioration in the quality of the milk produced

答案A

我就想问下 ，A中can do so 什么意思啊？

leiyu_52

can do so不知道什么意思怎么选对的这道题。。。 can do so在这句里就是can take hold. 某些危险细菌本来活不了（cannot take hold)，但是因为s. simulans的存在，这些细菌就能活了。（can do so,即 can take hold)

shunliqumeiguo

感激！！！