编辑点评： 新GRE阅读考试考察大家的方面较多，除了大家需要拥有一定的词汇量以外，还需大家在解题的时候能够迅速了解出题者的`意图，这就需要大家充分发挥自己的逻辑理解能力和推理能力，大家可以利用下文的新GRE阅读短文练习进行练习。
Certain extremely harmful bacteria found only in sewage are difficult to detect directly. Testing for E. coli, an easily detected and less harmful type of bacteria, in ocean water would be a reliable way of determining whether or not these more harmful bac-teria are present, since ocean water contains E. Coli only if the water is contaminated with sewage that contains the harmful bacteria.
Which of the following, if true, most seriously weakens the argument?
There are many different strains of the E. coli bacteria, and only some of these strains are harmful.
Some types of bacteria found in sewage are neither disease-causing nor difficult to detect directly.
Some of the types of bacteria found in sewage along with E. coli are not harmful to people unless the bacteria are ingested in large quantities.
E. coli dies out much more quickly than some of the more harmful bacteria found in sewage and then can no longer be easily detected.
Some of the types of bacteria found in sewage along with E. coli reproduce at a slower rate than E. coli.
