忽略了一个潜在的条件，邮票数x和y都为整，试数
15的倍数个位只可能是0或5；9的倍数就多了0到9都可能
假设15x个位是5，9y的个位就只能是5，y＝5，检验不可能得到x为整；y＝15，已经比440多了，排除
15x的个位只能是0，9y的个位只能0，y不能是0，y＝10只有一种可能

C.embark on sth开始着手做某事
Other towns and cities nearby have yet to embark on any comparable plans to attract new citizens.附近的城镇还未开始实施计划。——增强
have yet to do sth=have not yet done sth，尚未做某事
D.Most developers see the extra expense of providing municipal facilities as simply one of the many costs of doing business.
大多数开发商认为，提供市政设施的额外费用只是开展业务的众多成本之一。——语意偏增强

注意第二问是可以求的，知道R之后，2R-DE整体除以2可以求r

我是31号，有一起的没

有视频格式不支持或服务器问题看不了视频的朋友吗？

D选项 缺少了因果逻辑

错选A，
逻辑语意没get到。
A creatures were suffering是因为increasing temperatures.
B creatures were suffering是因为food supplies were dwindling , dwingling 的原因是increase in temperatures

E没有解释为什么游泳运动员中气喘的人比其他运动的要多

错选D，seeming(现在分词做定语 )and are（动词），这里are只能和tend to be并列

D为什么不对啊...很少有人因为座位服务问题不坐这个飞机，那也就是说这些人是因为其他原因不坐这个飞机。就算座位服务问题改善了，其他问题没改善，他们还是不会来坐这个飞机。卖出去的票不够多怎么cover cost，怎么提高利润....？

show约束力较弱，一般不加宾补

幸存者偏差

and , but ,or 合句
though引导让步状语从句，修饰主句动词，has
D，rats was fed a diet that has at least 30 percent fewer calories than they would normally eat
这里被比较部分省略了定语或比较的主体diet，than (the diet) they would normally eat，但不会引起歧义。
另一个例子：Rice has protein of higher quality than that in wheat.
That不能省略，因为比较的是 protein in rice VS protein in wheat,不是rice VS wheat

change 和shift语意重复。

or 用venn图思维来解 意思是只属于某一块的 即一个圆去掉重叠部分的剩余部分
1、younger than 40 取20+30+30=80
2、or supports a type of funding that incudes a tax 只取10（因为20已经包含在1里了）
3、or both 只取60（因为30已经包含在1里了）

80+10+60=150 150/250=3/5

TAKEAWAY:BF题主要从两个方面判断，一是性质：fact/prem/con（前后性质判断是否准确）,二是方向+/- (前后是否同向)

比较的双方必须概念对等
A，Lake Baikal, which holds 20 percent of the world's fresh water, more than all the North American Great Lakes combined.A do B, more than C可以表示A do B more than do C,也可以表示A do B, more than C do B,这里根据语意可知是后一种情况。可以看成是more than all the North American Great Lakes combined do，比较对象是水和水，ok。
(D) while作为连词表示当…的时候或者表示转折,而原句并没有这种逻辑关系; D，which指代20%的淡水，20%的淡水is more than all the lakes combined,将一定数量的水与湖比较，比较对象错误

C.It cites the most striking instance of historical change通常原文没提到的最高级、比较级的、夸大的选项都是错的

E.Targeting the most economically disadvantaged minority-owned businesses
只是过去的目标

In fact, in 1970 the SBA explicitly stated that their main goal was to increase the number of minority-owned businesses. Increasing the number of minority-owned firms was seen as a way to remedy this problem.