给出下列函数①$y=x\cos x$②$y={\sin }^{2}x$③$y=\left|x^2-x\right|$④$y=e^x-e^{-x}$，其中是奇函数的是（   ）

    While waiting for my daughter I treated myself with a coffee which I used to be so dependent on that when I stopped it I had headache for days. So while I was enjoying my rate moment, I was attracted by an old men who seemed not well

    I could not see his face to be sure, as it was laid between his folded arms on the table. He had a long warm coat, and a big backpack which made me think he could be a homeless. I quit wondering, went to his table, patted him on the arm and asked him, “Are you OK?” He raised his head and said something in a whisper, nodding yes. I realized by the strong smell that he was indeed a homeless man.

    I asked him if he was hungry. He responded but I could not understand his answer. However, I didn't give up and asked him if he would like some rice balls at which he raised his head saying clearly this time that he would be thankful for a rice bait Immediately I went to the nearest shop and bought a drink and a warm lunch box, and brought them to him. He said “thank you” but didn't eat right away and made no move, maybe because he was a little shy in the presence of a lady.

    So I left them on his table and changed my waiting place. When I passed again nearby, he was eating. You should have sensed my great pleasure. I was so grateful that I had the ways to help an old man even if only for a moment of his life.