肾实质中由肾小体、肾小管组成的部分称为肾皮质（肾单位）；由许多密集的肾小管组成的部分为（）。
参考答案：肾髓质
若u=f(xyz)，f(0)=0，f’(1)=1，且
，求u．
Which of the following statements is true according to what you hear
The Mediterranean region is cited as an example of .
A．the ability of nature to remedy human destructionB．the ability of people to make use of natural resourcesC．the manner in which people replenish the environmentD．the effects of human abuse of natural resources
，求u．