较难的盈亏问题有两类情形:一类是盈多少和亏多少,没有直接给出,需要通过计算或推理才能求出;另一类是两种方案里,每一种里又有两种方案。有时在一道题里这两类情形同时存在,不易辨别是否属于盈亏问题。 Difficult profit and loss problems, there are two types of situations: a category is how much profit and loss, not directly given, you need to calculate or reasoning can be obtained; the other is the two programs, there are two in each Program. Sometimes in a question where these two types of situations exist at the same time, it is not easy to distinguish whether the issue of profit and loss.