问题如下：
2. Based upon Exhibit 1, capital deepening as a source of growth was most important for:
选项：
A.Country A.
B.Country B.
C.Country C.
解释：
A is correct.
The associate economist can measure the effect of pure capital deepening by measuring the difference of the growth rates of labor productivity and total factor productivity (TFP). The larger the difference, the more important capital deepening is as a source of economic growth. From 2000–2010, Country A’s labor productivity grew by 2.4% per year, of which 0.6% came from TFP growth and 1.8% from capital deepening (2.4% – 0.6% = 1.8%).
考点：Cobb-Douglas production function 的变形公式
解析：先写出变形公式：
一国人均产出也就是劳动效率的增加来自于两个方面：资本深化以及技术的进步
Growth rate of labor productivity= Growth rate of TFP+ Growth rate of capital deepening（假设劳动力恒定不变）
capital deepening%=△y/y-△T/T
最后计算结果是A国的数值最高(2.4% – 0.6% = 1.8%).这就表明A国对于资本深化最依赖，资本深化对于该国经济增长的贡献最大。
老师想请问，想请问这题的公式是怎么变形出来的？
用的是变形① y=T * k^α
两边取对数
Lny = Ln T + α* Ln k
微分
△y/y = △T/T + △k / k 是这样吗 ？那这个式子跟变形三： △y/y = △T/T + α* （△k / k）+ (1-α）* （△L/L）是不是矛盾了~？还是我转换过程中有错误呢，请指出，谢谢。
