编制了“大明历”，并将圆周率精确推算到小数点后第七位的著名数学家、天文学家祖冲之是_

A couple of years ago, I went to Australia for a meeting with my friend, Chris. We decided to drive across country to Brisbane after the meeting ended. The drive was going to take four days and most of it was across the desert,    81   
The first day was a lot of fun as we were excited and laughing at each other’s stupid jokes. By the third day of driving in the seemingly endless desert, we began to get bored. We had been quiet for a few hours when in the distance Chris found some kangaroos. We were both excited and decided to get a closer look.   82  We got closer and closer, and Chris was doing 110 kilometers per hour. We were very close to the kangaroos—too close—when we heard a loud BANG!
Chris stopped the car and we got out. Behind the car was a larger kangaroo lying completely still on the ground.    83  He took off his sunglasses and put them on the kangaroo and did the same with his jacket. Then, he put his arm around the kangaroo and told me to take a photo of them together.   84  While I was focusing the camera, I saw the kangaroo move. It suddenly woke up, looked at Chris, and jumped away into the distance before we could do anything.
I started laughing but Chris looked very serious.   85   I started laughing even harder. I stopped laughing, however, when he said that our car keys were also in the jacket!

A. Chris speeded up to catch up with the kangaroos. B. He said his wallet and passport were in the jacket. C. In order to get there in three days, we drove very fast. D. so we had to take food, water, and extra gas with us. E. Chris went over to the kangaroo and put his baseball cap on its head. F. I was still surprised, but I took out my camera.