Gaze can also be considered from the perspective of necessary and sufficient conditions:

Let the content of the question be the condition 1 (if m is a positive integer and 3+ 16/m is an intermediate number less than 19). Which of the following statements about M is correct? That is to say, which of the following is the necessary condition for the condition 1 to hold: [Condition 1 hold => option has been established]. It is right to stare at some values of b, which shows that b is not a sufficient condition for the condition 1 to hold: [b holds = \ = > The condition 1 holds], but it cannot be denied that b is a necessary condition for the condition 1 to hold.

It is correct to stare at C, because C is a sufficient condition for the condition 1 to hold, but C is not a necessary condition for the condition 1 to hold (that is, what the landlord said is incomplete): [C holds => condition 1 holds], but [Condition 1 holds = \ =>c]

So if, as GGG _ 000 _ 11says, m = 2,4,8, 16, this is the necessary and sufficient condition for the condition1to hold: [m = 2,4,8,/kl] Condition 1 established], of course, everyone has no objection.

It's a little complicated. To sum up briefly, if you stare at this question, what you want to ask is not a necessary and sufficient condition, but only a necessary condition. Many of our common multiple-choice questions are necessary and sufficient conditions, so there will be some embarrassment here; However, one of the purposes of the SAT math test is to test the logical ability, so we should pay attention to it, especially the English question and answer, and carefully analyze it.