求助 3道数学题！！谢谢~~

Q10:

A set of numbers has the property that for any number t in the set, t + 2 is in the set.  If –1 is in the set, which of the following must also be in the set?

I.                    -3

II.                 1

III.               5

A.    I only
                    

B.    II only

C.    I and II only
                    

D.    II and III only
                    

E.    I, II, and III
                    

Answer: E  D  为什么不是D啊？？

A.      424

B.      433

C.      440

D.     449

E.      467

Answer: C

Q27:

If n = 8¹¹ – 8, what is the units digit of n?

A.      0

B.      1

C.      4

D.     6

E.      8

Answer: E C

后面这两道题是一个类型的，我对这种求位数的题找不到思路阿~~

恳求高人指点！！

Q14:100-74=26.其他的位都是9,即999......26,各位的和=9*48+2+6=440

Q27:8的N次方个位数是4,2,6,8循环,数到11就是2,....2-8个位就是4

我可不是什么高人,第二题的方法比较笨,希望NN指正.

Q10:

Both t and t+2 are in the set of numbers, where t =1 , t+2=3 is in the set .

where t=3, t+2=5 is also in the set. 

Thank you! So according to nanagi's solution. The answer to Q10 should be E!

...Why I can't type Chinese?!!