When I was five years old. I took a boat out on the river and went fishing by myself. I really wanted to catch a fish! But they were not biting.

    I stayed in my boat for three days, waiting. A few times, I thought I felt a fish at the end of the line. The first time I pulled in my catch, it was not a fish; it was an old bag. The second time, it was a shoe. Finally, at the end of the third day, I felt a strong pull at the end of the line. The pull was so strong they my boat raced around and around. I needed all my power just to hold onto the fishing rod. I pulled, and I pulled and I caught the biggest fish that ever swam on the Earth! It was heavier than everyone in this room put together! Then something terrible happened!

    After I pulled the huge fish into my boat, I saw that the boat was going under water! Water was coming into the boat from all sides! I was not a very good swimmer, so I was scared.

    Although it was the hardest choice I ever made. I had to let the fish go. I pushed it back over the side of the boat, and we waved good-bye to each other as it swam away.

①这个关键少数是事物的本质和主流

②关键部分的功能及其变化甚至会对整体的功能起决定作用

③主要矛盾对事物的发展起决定作用

④全面深化改革任务的确定和落实需要运用综合的思维方式

用图甲、乙两种方式匀速提升重为100N的物体，已知滑轮重20N、绳重和摩擦力不计。则（ ）

已知实数x，y满足$\left\{\begin{array}{c}\begin{array}{c}y\le x\\ x+2y\le 4\\ y\ge -2\end{array}\\ {\left(x+1\right)}^2+{\left(y-1\right)}^2=r^2\left(r>0\right)\end{array}\right.$，则r的最小值为（   ）