问题
单项选择题
Bowls X and Y each contained exactly 2 jelly beans, each of which was either red or black, One of the jelly beans in bowl X was exchanged with one of the jelly beans in bowl Y. After the exchange, were both of the jelly beans in bowl X black ？（）
(1)Before the exchange, bowl X Contained 2 black jelly beans.
(2)After the exchange, bowl Y contained 1 jelly bean of each color.
A．条件(1)充分，但条件(2)不充分．
B．条件(2)充分，但条件(1)不充分．
C．条件(1)和(2)单独都不充分，但条件(1)和条件(2)联合起来充分．
D．条件(1)充分，条件(2)也充分．
E．条件(1)和条件(2)单独都不充分，条件(1)和条件(2)联合起来也不充分．
答案
参考答案：E
解析：
(1)不充分，因为Y碗中的果冻豆的颜色未知；(2)同理也推不出交换之后碗X中含有的果冻豆的颜色；(1)+(2)同样无法回答上面的问题，因为交换前Y碗中的果冻豆的颜色未知。