4-6：Dear editor,

     I'd like to talk about four important inventions in human history.They are the medicion,plane,train and computer. 

    When we're ill, we should take medicine. It can stop us from getting sicker. It has made it possible for us to live longer.

     Mostly we take the plane or train to go to very far places. They have made it more convenient for us to go out.

     The computer was invented in the 20th century. It is used by us to study,work or relax.It has made our lives more convenient and colorful.

    I can't imagine what our life will be like without the four inventions.

    Yours,

Chen  Hui