Must Be X vs Cannot be true

[lathlee]

As I was going through some of the wrong questions that i got in the 2016 version of RC LSAT powerscore, I realized that the wording of Must be X and Cannot be true are pretty similar to possibly the same.

How can I distinguish the two?
also, in RC only, Must be X and Cannot be True questions' answers, Is the correct answer are basically the same ?

[Dave Killoran]

Hi Lathlee,

They aren't identical, but do overlap. Here's how:

Must Be True Except:

Incorrect answers: Must Be True
Correct answer: Not Necessarily True (which includes Cannot Be True)

Cannot Be True:

Incorrect answers: Could Be True
Correct answer: Cannot Be True

So, the two aren't identical. In the LRB, look up the discussion of the Logical Opposition (LGB has it too). These ideas are covered in detail there!

Thanks!