Methane is a colorless, odorless and flammable substance which forms a major component in natural gas.

甲烷是一种无色，无味，易燃物质，是天然气的重要组成部分。

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Oxygen is the second largest component of the atmosphere, comprising 20.8% by volume. Gaseous oxygen is colorless, odorless, tasteless, and nonflammable.

氧是空气的第二大组成成分，体积占20.8%。气态氧无色，无嗅，无味，不可燃。

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The colorless, liquid component of the cell nucleus.

无色，液体组成部分细胞核。

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CO2 is a colorless and odorless gas, exhaled at high concentrations by each of us, and a key component of the biosphere's life cycle.

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