| A | B |
|---|
| invention | The light bulb was an __ that helped people do things at night. |
| experiment | First, an inventor must perform an ___ to test an idea. |
| laboratory | Scientists may test their ideas in a ___. |
| genius | Albert Einstein was a ___. |
| gadget | A small ___ with many parts can be hard to repair. |
| electric | The invention of the __ fan helps us stay cool in hot weather. |
| signal | A red light is a ___ to stop. |
| occasional | A good invention has an __ problem but should not fail regulary. |
