题目是问你P(A+B) = P(A) + P(B) - P(AB)

1. P(AB)=0是不充分的.因为如果同时发生的概率为0那么说明白球上都不是偶数,但是不代表不是偶数的都是白球.所以不充分

所以锁定选项B/C/E

2. 白球的概率-偶数概率为0.2,P(A) - P(B) = 0.2 .无法解出 P(A) + P(B)

所以两个加起来也不充分

读懂题。不是一共花了9100，是有9100可以花，就是可以实际的比这个少。。。汗。

此题不用标准差的计算公式。

Ron- "the increase in X" means that X itself has increased. therefore, "the increase in the previous year" doesn't make sense, because the implication would be that the previous year itself had increased (what would that possibly mean?).

"the increase of TIME PERIOD", by contrast, means exactly what it should mean in this particular instance.

三角形：两边之差

看清！2 是shipping fee

由1，k=36，27，38，39，或者40，41，42， 43 44 所以k的十位不确定。
由2，k的个位数>5,则k+5的个位数要进一位，得到4，故k的十位是3.所以2充分。1不充分。

至少100个学生学日语。。
1. 至少
2. 日语。

一堆零，仅有一个非零的情况。不分奇偶。

c climate change 存在，krech的反驳是climate change 是一个影响因素，c增强了
krech 的观点

不知道怎么错的了。0也是整数。

1) p/4 为质数，则p可以为很多数。2）同一；1+2 p可以被4整除，也可以被3整除，那么p可以被12整除，因此p可以是12的倍数（12，24，48，60...) 。但是需要满足p/4是一个质数，因此只有12满足条件。

intermettent conclusion

Some residents voiced concern that the rice could threaten certain species of rare migratory birds. -----migration
c。。few species of birds native to the province normally eat rice.----native

c不是独立主格，with后面跟的是动名词和名词，由于的意思，相当于because of 和as a result of。。后面通常加纯名词，而不是ing，也不能加从句。

The storms most studied by climatologists have been those that are most easily understood by taking atmospheric measurements.

Northeasters, whose diffuse nature makes them difficult to categorize, are relatively weak low-pressure systems with winds that rarely acquire the strength of even the smallest hurricane

topic sentence:But other equally destructive storms have not been so thoroughly researched, perhaps because they are more difficult to study.

做题的时候一直在纠结state与country，这个题意绕啊绕到底怎么make sense。。欺负非native不懂基础知识。。。

生活好艰辛！