Many objects that people use each day started with a simple idea. These objects have often changed the way we  46  . Some help us to do a job more   47  . Others fill a need or solve a problem.
In 1858, Lipman had such an  48  . He took out a pencil, a piece of paper,   49  an eraser. Then he began to write. Sometimes he needed to  50  a word. Each time he had to search under his books and papers to   51   the eraser. “ I wish my eraser would stay in one 52  !” he said.
Then Lipman had his simple idea. He   53  a groove(凹槽) in one end of the pencil. He glued(粘牢) the eraser into the groove. Lipman had solved his problem. Later he thought that others might like to have such a pencil. So he sold his  54  .Some pencils with erasers were 55  . His design earned $ 100000.

A．study B．live C．sleep D．walk

A．easily B．correctly C．carefully D．normally

A．article B．aim C．idea D．action

A．so B．and C．but D．as

A．spell B．read C．write D．change

A．look B．see C．watch D．find

A．place B．desk C．book D．hand

A．marked B．prepared C．cut D．invented

A．books B．pencil C．design D．eraser

A．wonderful B．expensive C．colourful D．common