此类型题目按照问题的不同又可细分为两类:what型和yes or no型,即特殊疑问句型和一般疑问句型。前者对于充分的要求是可以得到唯一的实数解,非实数或不唯一均不充分,即要求的解集是只有一个实数元素的集合,此时,所得解集只能与要求解集相等;后者则要求可以回答是或不是,即肯定充分和否定充分,此时千万不要将回答的肯定或否定与附加条件的充分与否相混淆,即使得到的是否定的回答,此条件也是充分的,并且两条件分别单独充分时,不要求对问题的回答一致。
附:
DS choices:
A.Statement (1) alone is sufficient, but statement (2) alone is not sufficient to answer the question asked;
B.Statement (2) alone is sufficient, but statement (1) alone is not sufficient to answer the question asked;
C.Both statement (1) and (2) together are sufficient to answer the question asked, but neither statement alone is sufficient;
D.Each statement alone is sufficient to answer the question asked;
E.Statements (1) and (2) together are not sufficient to answer the question asked, and additional data are needed.