[求助]几道数学题，希望大牛给予指点````````````````````````````

gill0324

1.Susan has selected exactly three crayons, each a different color, from a crayon box.How many crayon colors were represented in the box before her selection?(C)

(1)Exactly four distinct three-crayon color combinations were represented in the box before Susan selected three crayons.

(2)Just before Susan's selections,the box contained exactly five crayons.

A.Statement 1 ALONE is sufficient,2 is not.

B.Statement 2 ALONE is sufficient,1 is not.

C.Both 1 and 2 TOGEHTER are sufficient,but NEITHER  ALONE is sufficient.

D.EACH ALONE is sufficient.

E.1 and 2 TOGETHER are NOT sufficient.

这题不明白意思，希望能讲解下。

2.If the product of two integers x and y is negative,what is their difference?(E)

(1)x+y=2

(2)-3<x<y.

A.Statement 1 ALONE is sufficient,2 is not.

B.Statement 2 ALONE is sufficient,1 is not.

C.Both 1 and 2 TOGEHTER are sufficient,but NEITHER  ALONE is sufficient.

D.EACH ALONE is sufficient.

E.1 and 2 TOGETHER are NOT sufficient.

请问划线部分是什么意思？什么是x和y的不同？这题为什么选E？我觉得应该选D

3.Three salespeople--A,B,and C--sold a total of 500 products among them during a particular month.During the month,did A sell more products than B sold as well as more products than C sold?(A)

(1)A sold 166 products during the month.

(2)C sold 249 products during the month.

A.Statement 1 ALONE is sufficient,2 is not.

B.Statement 2 ALONE is sufficient,1 is not.

C.Both 1 and 2 TOGEHTER are sufficient,but NEITHER  ALONE is sufficient.

D.EACH ALONE is sufficient.

E.1 and 2 TOGETHER are NOT sufficient.

对于划线部分我的理解是A比B和C卖的都多，但是如果A卖出了166个，那么B和C肯定有卖的比A多的。请大牛指点。

dabobowa1111

第二题的，differenc指差。

其他的题求nn出现

gill0324

谢谢你，第2题我明白了，因为xy有-2，4；-1，3两种可能所以选E