:一般现在时的用法是怎么样的

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  I don't want so much.
  Ann Wang writes good English but does not speak well.
  比较：Now I put the sugar in the cup.
  I am doing my homework now.
  第一句用一般现在时，用于操作演示或指导说明的示范性动作，表示言行的瞬间动作。再如：Now watch me, I switch on the current and stand back. 第二句中的now是进行时的标志，表示正在进行的动作的客观状况，所以后句用一般现在时。