51. The unlined sentence “I never made a penny until I stopped working for money. ” in Paragraph Four refers to “__________”.
    A. I wouldn’t work unless I could make money
    B. I believe that my work will be rewarded
    C. Working for money is what I love to do
    D. Working for money makes no money at all
52. The main idea of the last paragraph is ___________.
    A. we should try heart and soul to win what we want
    B. enthusiasm can give us pleasure, though we have to sweat
    C. we have not enough money to buy what we need
    D. enthusiasm with sweat is what we need

                                D
    How men first learned to invent words is unknown; in other words, the origin of language is a mystery. All we really know is that men, unlike animals, somehow invented certain sounds to express thoughts and feelings, actions and things, so that they could communicate with each other; and that later they agreed upon certain signs, called letters, which could be combined to represent those sounds, and which could be written down. Those sounds, whether spoken, or written in letters we call words.
　　The power of words, then, lies in their combinations — the things they bring up before our minds. Words become filled with meaning for us by experience; and the longer we live, the more certain words recall to us the glad and sad events of our past; and the more we read and learn, the more the number of words that mean something to us increases.