例: If I were rich, I would buy a big house.
（もしお金持ちだったら、大きな家を買うのに。）
2. 仮定法過去完了（過去の事実と違うことを言う時）
公式: If + 主語 + had + 過去分詞, 主語 + would/could + have + 過去分詞
例: If I had studied more, I would have passed the test.
（もっと勉強していたら、テストに合格していたのに。）
3. I wish / If only（「～だったらなあ」）
今の願望: I wish + 過去形
例: I wish I were taller.（もっと背が高かったらなあ。）
過去の後悔: I wish + had + 過去分詞
例: I wish I had studied more.（もっと勉強していたらよかった。）
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In autumn, leaves change color because of changes in weather and daylight. Trees absorb sunlight through their leaves, which contain a pigment called chlorophyll. Chlorophyll gives leaves their green color and helps trees produce food through photosynthesis.
As autumn arrives, days become shorter, and the temperature drops. Trees start to prepare for winter by slowing down their food production. This means they stop making as much chlorophyll, and the green color fades away. As the chlorophyll disappears, other pigments in the leaves, like carotenoids, become visible. Carotenoids give leaves their yellow and orange shades.
This process helps trees conserve energy and water during the colder months when sunlight and water are limited. Eventually, the leaves fall off, allowing the tree to survive through winter and grow new leaves in spring.
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