| Aha! | |
| Greenhouse | |
| A greenhouse is a building with walls | |
| and a roof made of glass or vinyl. | |
| People build greenhouses to create an environment | |
| where plants can grow under a controlled climate. | |
| This idea of growing plants in an artificially controlled | |
| area has existed since ancient Roman times. | |
| The Roman emperor Tiberius ate a cucumber-like | |
| vegetable every day. | |
| Roman gardeners used artificial | |
| methods to have it available at his | |
| table throughout the year. |
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