问题
单项选择题
If 
, where a, b, and c are each equal to 0 or 1, then x could be each of the following EXCEPT:（）.
A.A
B.B
C.C
D.D
E.E
答案
参考答案：D
解析：
The most direct way to address this problem, since there are only eight possible values for x, is to determine all the possible values and then check them against the possible answers, x could equal 0, 1/27, 3/27(=1/9), 4/27, 9/27(=1/3), 10/27, 12/27(=4/9), or 13/27. The only answer not among these choices is D, 2/9.