GWD数学第九套的几个问题，做数学时候的问题，谢谢了

wly1202m

GWD数学第九套里面，有几个题目没理解，请教下大家，谢谢了^-^

Q10.
What is the value of (x - y)4?
(1)      The product of x and y is 7.
(2)      x and y are integers.
    
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
答案选C....太奇怪了. 怎么x和y都是整数，但xy相乘等于7.....怎么可能啊？

Q26.
In the decimal representation of x, where 0 < x < 1, is the tenths digit if x nonzero?
(1)      16x is an integer.
(2)      8x is an integer.
    
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

答案选B

大家， 我现在做GWD的数学套题，感觉时间还是有点紧：1. 是因为算错了，导致重新算，时间双倍耗费了；2. 经常一道题没做出来，一直耗时间，但是又不舍得放弃（大体什么样子的题目可以果断放呢？我感觉努力下都可以做出来。。555）；导致一般最后10几题时间压力都特别大... 还有一次没考完（剩4题）....
大家有没有什么建议给我的。。马上考试了。。谢谢大家了
（我也有想过，如果考场上碰到JJ的话，难点的题可能会更顺利点）

liuyin

What is the value of (x - y)4? 是不是少了点什么东西？PS：xy=7, x,y为整数。则：x=1,y=7, x=-1,y=-7;x=7,y=1;x=-7,y=-1

liuyin

Q26, 0<8x<8; 8x为整数，8x范围：1-7; x范围：0.125-0.875；tenths digit非0