PREP 求解？

chinamerica

一种化学反应速率与 A的浓度的平方成正比，与B的浓度成反比。
如果B的浓度增加100％，问A的浓度要增加多少才能使化学反应速率维持不变。

设化学反应速率为r，A的浓度为a, B的浓度为b.
则 r= k a^2 /b,  where k 是常数  
B的浓度增加100％，i.e., b-> 2b
如果r维持不变的话，a^2 需要变到2a^2,i.e, a需要变到 {\sqrt 2}a, 差不多1.414a, 也就是说a需要增长41.4%左右。

The Achaemenid empire of Persin reached the Indus Vally in the fifth century BC, bringing the Aramdic script with it, from which was derived both northern and southern India alphabets.

先看逻辑意思主要看从句到底是修饰什么..  从句中  both northern and southern India alphabets derive from sth...
sth 应该是the Aramdic script.  注意到从句是倒装结构哈
A. the Aramdic script with it, from which was derived both nothern and   从句指代错误
b. the Aramdic script with it, and from which was derived both nothern and the  从句指代错误
C. with it the Aramdic script, from which derive both the northern and the   正确
D. with it the Aramdic script, from which derives both northern and   ‘both northern and southern India alphabets’ 应该用复数动词derive
E. with it the Aramdic script, and deriving from it both the northern and  这里deriving from it....与前面的bringing.....平行，但显然这里bringing 和 deriving 的主语不可能都是'empire'