问题
单项选择题
What is the maximum capacity in cups of a pail that contains only sand and is filled to three fourths of its capacity ？（）
(1)If one cup of sand were added to the pail, it would be filled to seven eighths of its capacity.
(2)If two cups were removed from the pail, it would be filled to one half of its capacity.
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：D
解析：
设这个桶的容量为a杯，则桶中的沙子为[*]，根据(1)可得：[*]，从而可以求出桶中的沙子是6杯，所以(1)充分；根据(2)可得[*]，从而可以求出桶中的沙子是6杯，所以(2)也充分。