根据短文内容，选择正确答案。
A
    One day, Mr. and Mrs. White went shopping by car. They stopped their car near a store. They bought a lot of things and they wanted to put them in their car. But Mr. White couldn't open the door of the car. “Let's ask a policeman for help.” said Mrs. White. They asked a policeman to help them. The policeman was very friendly to help them open the door of the car. Just then a man came up and shouted, “What are you doing with my car?” Mr. and Mrs. White took a look at the number of the car. It was not their car.

已知$\left\{a_n\right\}$是等差数列，且$a_2+a_5+a_8+a_{11}=48$，则$a_6+a_7=$(    )

设复数满足(1-i)z=2i,则

谚语：世界是一棵树，人是它的果实。这主要说明了（    ）

造成当今环境质量下降，生物多样性面临威胁的根本原因是（    ）