A. DIRECTIONS: Read the passage and answer the questions that follow.

Our bodies are adapted to Earth's gravity. Our muscles are strong in order to overcome gravity as we walk and run. Our inner ears use gravity to keep us upright. And because gravity wants to pull all our blood down into our legs, our hearts are designed to pump hard to get blood up to our brains. In space, the much weaker gravity makes the human body change in many unexpected ways. In microgravity, your blood is rerouted, flowing from the legs, which become thin and sticktike, to the head, which swells up. The extra liquid in your head makes you feel like you're hanging upside down or have a stuffed-up nose. from "Life Without Gravity" by Robert Zimmerman

1. What is the main idea of the passage?
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2. Name two details that support the main idea.
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3. Write a brief summary of the passage on the lines provided.
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