问题
单项选择题
Four cups of milk are to be poured into a 2-cup bottle and a 4-cup bottle. If each bottle is to be filled to the same fraction of its capacity, how many cups of milk should be poured into the 4-cup bottle ？（）
A.A
B.B
C.C
D.D
E.E
答案
参考答案：D
解析：
设倒入4杯瓶中的牛奶有x杯，根据题意可得
。