已知函数f（x）定义域为（0，+∞），且满足f（x）+xf′（x）=$\frac{\ln x}{x}$，f（e）=$\frac{1}{e}$则下列结论正确的是（　　）

Zhao Yan: Look at this photo, Wang Ying.

Wang Ying: Oh, I remember. It was Liu Ning, you and I that were at the gym. It was rainy that day. We went to the gym to watch Lin Dan play badminton. He played with a player of Australia. We yelled for Lin Dan. He played very hard. Finally he won. We were happy. We jumped up and down.

⑴Zhao Yan, Liu Ning and Wang Ying ____      A. happy.

⑵They watched ____                          B. won.

⑶Lin Dan played with ____                    C. were at the gym.

⑷Lin Dan ____                                D. a player of Australia.

⑸We were ____                               E. a badminton game.

洒水车在水平路面上匀速前进并洒水时，它的动能____，机械能____。(选填“变大”“变小”或“不变”)