单项选择题
杯里全是水,倒出装入纯酒精,又倒出装入纯酒精,再倒出装入纯酒精,问现在酒精浓度是多少()
A.60% B.36% C.50% D.40%
A.105/228 B.30/228 C.137/228 D.135/228