History

3. all of the engines used by people today are creating a terrible _____for the Earth.
7. was a great scientist from the 20th century.
10. the ____ was invented in the 20th century
11. There were two very big wars in the 20th century. They are called World_____I and World _____II.
12. Important medicines and medical tools, like the _____
13. train, plane or ____

1. Today people travel from place to place by
2. were invented in the 20th entury, too.
4. is a liquid that is burned to make power in an engine.
5. is one hundred years
6. An engine is a machine that can use heat_______to create motion.
8. If people do not change soon, we may hurt the _____ very badly
9. A lot of you probably ride on a scooter or in a car. Both of these _____were invented in the 20th century
11. The energy made by burning ______could make a wheel turn