Do you know the Chinese saying “He who doesn't reach the Great Wall is not a true man”? Mr. White knows it. Next month he is going to Beijing with his wife. They are going to visit the Great Wall. They are staying in Beijing for about a week. They have a lot of Chinese friends there, so they are visiting them. Then they're flying to West Lake in Hangzhou. They are going boating there and staying there for about three days. Mr. White knows that the Yellow Mountain is very famous in China. So they’re going to Anhui to go hiking in the great mountain. After two days in Anhui they'll have to go back to Sydney.
   “I'm taking lots of photos in China. When I get back to Sydney, I am going to show the photos to my friends. I want my friends to know more about China.” said Mr. White.

函数f(x)=x²e^-x在1,3上最大值为(   )

如图所示是斜向上抛出物体的运动轨迹，C点是轨迹最高点，A、B是轨迹上等高的两个点．下列叙述中正确的是（不计空气阻力）（   ）