diameter圆直径20 radius半径10 面积100π
正方形边长24 面积24^2
求两者面积比
100π/(24^2) 最接近1/2

1/2 *2/3* 1/2 *1=1/6

Each statement is giving saperate information about sets X & Y
thus alone they are insuff

Combining we can choose any set
Case 1)
x= {1,3,5,7,9}
Y= { 2,4,6}
thus we have a YES to the question asked ie greatest integer in X greater than the greatest integer in Y
case 2:
x= {1,3,5,7,9}
Y= {10,12,14}

thus we have a NO to the question asked ie greatest integer in X is not greater than the greatest integer in Y

by ron:
choice b is correct: it uses a nonessential modifier set off by commas ('of up to 600 rooms each'), which, if eliminated, yields the intact and legitimate sentence ...carefully engineered structures, connected by... (with another nonessential modifier).

设总的population 是R，0.64R被雇佣，0.48是被雇佣的男士，则0.64R-0.48R=0.16R是被雇佣的女士，0.16R/0.64R=25%，即被雇佣的女士在总的被雇佣人数中所占比例。

t + 2 is in the set，断定了只能向后推不能向前推，无法断定t-2是否一定存在在集合里

设一共有x女人，则一共有1400-x男人，由（1）可得：36%*（1400-x）+50%x=42%*1400。条件2没有给出男女比例无法算出

m-5=n(n-1)，判断n(n-1)为偶数，odd-5=偶数，可以得出m=odd

mark，列不等式解

不仅要考虑正负，还有条件并没有给出整数，所以要考虑非整数的情况

题目： n=1*2*3*4.....*20
2^k is a factor of n, 也就是问上面乘积有几个2
=》2*4*6*8*10....*20 (把奇数剔除）
=2^(1+2+1+3+1+2+1+4+1+2)=2^18

mark，不能随意消除(m-k)

1/3*2/3*1=2/9

实在不行就用枚举法吧。。一个个可能列出来

请问a里的and的前面的逗号可以去除吗？

an=a1xq^(n-1)

长见识了

A：composer不可能goes into decline，应该是reputation
B：never regains its status again的主语应该是reputation,而不是composer，错误的并列
C：正确罗列composer的两件事：receives 和reputation declines，以及reputation的两个状态： declines和 regains

regain和again重复

错选D