如图，点A坐标为（﹣2，3），将点A绕原点O顺时针旋转90°得点A′，求A′的坐标．

阅读理解

    When I was a child, I often dreamed of the time when I could leave home and escape to the city. We lived on a farm, in the winter especially, we wear quite out off from the outside world. As soon as I left school, I packed my bags and moved to the capital.

    However, I soon discovered that one big disadvantage is money. It costs so much to go out, not to mention basics like food and housing. Another disadvantage is pollution. I suffer from asthma(哮喘), and the air is so bad that I am afraid to go outside. Then there is the problem of traveling round. Although I have a car, I seldom use it because of the traffic jams. One choice is to go by bicycle, but that can be quite dangerous.

    Of course there are advantages. First, there is so much to do in the city, whatever you tastes in culture or entertainment(娱乐活动). Besides, there are wonderful jobs and greater chances of moving to a more important job or position. Finally, if you like shopping, the variety of goods is very surprising — and, what is more, shops are often only a short walk away.

    Is life better then, in the city? Perhaps it is, when you are in your teens(十几岁) or twenties. However, as you get older, and especially if you have small children, the peace of the countryside may seem preferable. I certainly hope to move back there soon.

“工程菌”是指    (　　)