Ⅲ.综合运用

The QWERTY Keyboard

Look at your computer keyboard.Have you ever wondered why the letters are not in alphabetical o__1__?

To answer this question，let's t__2__the clock back.About 150 years ago，all letters and papers were written by hand.Things were slow and messy（乱糟糟的）.

Some inventors built a typing machine.The first typewriters were big and heavy.They w__3__like a piano.

Have you ever seen the inside of a piano？You press a key and some levers（杠杆）will make a hammer（音槌）hit the right string（弦）to make a sound.Early typewriters were s__4__.They had many levers.At the end of each lever，there was a letter.Press the A key and the A lever would hit the paper and type A.The paper then moved a bit to the left.Press more keys and you could type a word or even a book.

The first typewriters had the keys in alphabetical order.There was a problem:If you p__5__two keys quickly,the levers would easily jam.

To reduce jams，people tried to rearrange（重新排列）the letters.American inventor Christopher Sholes invented the QWERTY keyboard.It t__6__out to be a great success.People around the world learned to use the keyboard.

Many other key arrangements have since been tried.Some are c__7__to be faster to use.However,none has been good enough to beat QWERTY.It is very difficult now to get people to change to any other key arrangement.

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