Viruses can have beneficial effects. For example, some kill more-complex microorganisms, some of which are deadly to...

colleen_ April 30, 2020

Once I read the reasoning why an answer is correct I usually understand, but am still not getting many right answers on my own. I was also pretty good at the Must be True questions.

shunhe May 3, 2020

Hi @colleen_,

Thanks for the question! Cannot Be True questions are differently a pretty interesting bunch, since you have to find an answer that cannot be true in any circumstances. A lot of the time, careful diagramming can get you to the answer. For example, if we know that

A—>B

Then what can’t be true? Well, A & ~B can’t be true, because A has to lead to B. This is just an abstract example of how diagramming can help you a lot with these questions. The answer is one that will HAVE to be wrong no matter what based on logical necessity. Or sometimes, an answer choice will flat out contradict a premise given in the stimulus.

Take this question you commented on for example. We know that there are viruses that kill more-complex microorganisms that are beneficial. But (E) tells us that no virus that is deadly to organisms of greater complexity than itself is beneficial to humans. This clearly contradicts the first couple of sentences in the passage, and so we can pick it immediately. After a bit of practice, these kinds of observations will come much more naturally. But generally, trying to test answer choices to see if they could be consistent with the passage is helpful.

Hope this helps! Feel free to ask any other questions that you might have.