题目内容：
The keyboard of a typewriter refers to the set of keys in it. Most typewriters have "qwerty" key-boards. The name comes from the first six letters on the board's second line. The "qwerty" board wasset up by C. L. Sholes, who was the first man to make a really good typewriter. Some letters, such as S and T, are used together a great deal in English. Sholes placed suchpairs of letter far apart on his keyboard. This made it harder for typists to learn the keyboard. But ithelped keep typewriters from jamming. On early machines the bars holding the letters often caught oneach other when moving quickly.
Sholes made the name of his machine easy to type. He placed on the same line all the letters ofthe word "type" and "writer".
根据以上内容,回答题.
（ ）This article is mostly about a __________. A．pair of letters
B．keyboard
C．language
D．man's life
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答案解析：