How men first learned to invent words is unknown;     1    , the origin of language is a mystery. All we really know is that men, unlike animals, somehow invented certain     2    to express thoughts and feelings, actions and things,     3    they could communicate with each other; and that later they agreed upon certain signs, called letters, which could be     4    to represent those sounds, and which could he written down. Those sounds, whether spoken,     5    written in letters, we call words.
    The power of words, then, lies in their     6    —the things they bring up before our minds. Words become     7    with meaning for us by experience; and the longer we live, the more certain words     8    to us the happy and sad events of our past; and the more we read and learn, the more the number of words that mean something to us     9    .
    Great writers are those who not only have great thoughts but also express these thoughts in words which appeal powerfully to our minds and emotions. This     10    and telling use of words is what we call     11    style. Above all, the real poet is a master of     12    . He can convey his meaning in words which sing like music, and which     13    their position and association can     14    men to tears. We should, therefore, learn to choose our words carefully and use them accurately, or they will     15    our speech or writing silly and vulgar. 
 
【正确答案】 B
【答案解析】 mystery与unknown同义,后一句话只是前一句的另一种表述,因此in other words“换句话说’,符合语境。in addition"并且,而且”,表示递进关系;in a word和in summary表示“总之”,说明概括和总结关系,均不符合题意。故选B。