下列词语书写完全正确的一项是（     ）

锌片：Zn＋2OH^－－2e^－=ZnO＋H₂O；

碳棒：O₂＋H₂O＋2e^－=2OH^－，

据此判断，锌片是(　　)

    It is Saturday afternoon. Liu Tao and his friend David are taking a walk in the park. There are many public signs in it. They mean different things. Liu Tao knows a lot of things about them. Suddenly, they see a short man walking on the grass. Liu Tao points to the sign on the grass and says to him, "Sir, look at the sign! You can't walk on the grass. "The man smiles and says, "You are right, young man. But I'm the park keeper. I'm looking after the grass. "

请根据你对“微笑”的理解，仿照画线的句子，再写两句，要求句式相同，运用恰当的比喻。
      朋友，你会微笑吗？微笑是一杯浓浓的咖啡，               ，               ，微笑是一曲动人的音乐。微笑让我们的生活充满了温馨。