第一次选择为 1/2（四个里面任意选一个白色的）， 第二次选择为2/3（剩下3个里面选择红色的），第三次选择为 1/2 （两个里面选则红色的），第四次选择为1。所以就是 1/2 *2/3* 1/2 *1=1/6

第一个是整数分数
第二个是 正负数问题

1）x^2+y^2和z^2都是正数
（x^2+y^2)^2=x^4+y^4+2x^2y^2>z^4，但不能推出x^4+y^4>z^4
2)x,y，z的符号不确定，不能判断
1）+2）只能知道x^4+2x^2y^2+y^4>z^4,不能判断x^4+y^4与z^4的大小

If he is to ride 3 times and since he can choose any of the 3 cars each time, total number of ways is
= 3 * 3 * 3
= 27

Now the number of ways if he is to choose a different car each time is
= 3 * 2 * 1
= 6

So the probability is
= 6/27
= 2/9

C,D选项用了but; but 为coordinating conjunction， 同 and和yet, 前后必须有并列结构

错选A: revealed an error in previous measurements这些科学家之前从来没有测量过温度，只是预设了一个估计值

题干有each year首先排除ABC, 和annually赘余。D中through improving performance of workers 可理解为伴随状语连词+ving，所以逻辑主语是companies in the US，但是提高工人的表现不是公司，而是比如说高科技啥的，所以D不对。E中through improved worker performance不存在这个问题。D中in employee illness prevention是状语，在预防疾病方面也讲的通，E中是by preventing illness among employees也是状语，逻辑主语companies也可以讲的通，所以我认为这不是考察的点。不知道我的理解对不对？

错选A，全文并没有评估Byerlee的试验方法

Geologists therefore wondered whether the friction between the plates was being reduced by pockets of pressurized water within the fault that push the plates away from each other.目前仍然没有明确的理论可以解释那些消失的热量

C: indicate that when a child acquires language, thinking, and emotional skills, 后面又跟了一个that从句，没有相应的主句

E:the second presents a situation that the argument contends must be changed, 必须要更改的并不是situation

D中when placed in a stimulating environment & when they learn new songs都是状语，修饰的是动作，即主句的动词，当时间状语，这个意思就不对了，它不是用来修饰动词的

little of加不可数名词

P:当第一次维修结果不满意，在保质期内可以送去第二次维修。往往第二次维修的结果都是让顾客满意的
C：这种现象的原因是精密维修所需要的专注度在二次维修中更容易被引发出来，比起第一次维修
argument给出的原因是concentration不一样，assumption的方向就是否定另一个可以解释premise里的现象的其他原因

还原E选项：drivers will be as likely to exceed the proposed speed limit as they are likely to exceed the current one

主谓不一致都没看出来~~~~E啊，找核心词刷掉一大片

Yet another explanation blames the federal budget deficit: if it were lower, interest rates would be lower too, thereby increasing investment in the development of new technologies, which would spur productivity growth in the service sector.

Neuroscientists的归类判断是根据ethologists的归类判断取反

数字只能比大小，所以首先排除DE.

句子中的某一个成分都由一个核心词担当