I want to be a scientist when I grow up.

Meaning: This means you want to study and do experiments to learn more about the world when you become an adult.

Choice of Words: Scientist is a person who studies and does experiments to learn more about the world. Grow up means to become an adult. When you put them together, "I want to be a scientist when I grow up" means that you want to learn more about the world and become an adult who does experiments.

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Related Expressions