"I will think of it"．It is easy to say this．（1）

C

C

   Sir Isaac Newton was sitting in his garden when he saw an apple fall（掉落）from a tree．（2）

D

D

Then he found how the sun，the moon and stars stay in their places．
   A boy named James Watt sat quietly by the fire and watched the lid（蓋）of the kettle（水壺）move up and down．He wanted to find out why the steam（蒸汽）in the kettle moved the lid．From that time he kept thinking and thinking．And when he became a man，he made the steam engine（發(fā)動機）better．（3）

B

B

   James Ferguson was a poor boy．When he saw the inside of a watch，he was thinking，"（4）

A

A

" But how could he make the main spring（主發(fā)條）？He soon found he could make it with whalebone（鯨骨）．He then made a wooden clock．His motto（座右銘）was "I will think of it"．And he made his ideas useful to himself and the world．
   （5）

E

E

Just think by yourselves．

A．Why couldn't I make a watch？ B．So it could easily do the work of many horses． C．But do you know what great things come from thinking？ D．He began to think and tried to find out why the apple fell． E．When you have a difficult lesson to learn，don't ask someone for help．