在英語學習中，外研版七年級下冊導航學英語M12U3的練習題對于理解相關知識點至關重要。以下是部分答案供參考：一、選擇題答案：1. C 2. C 3. D 4. B 5. A 6. D二、填空題答案：1. She spends two hours going / It takes her two hours to go2. has become part of3. is harmful to our health4. spends so much time on computer games5. you'd better stop working6. It's good for your health三、閱讀理解答案：1. It will become hot and there will be pains all over.2. Because they are very small.3. We can find them everywhere.4. It will become big and red.5. It mainly tells us what germs are and where they are.四、選擇題答案：1. B 2. C 3. D 4. C 5. A 6. C 7. A 8. D 9. B 10. B這些答案可以幫助學生更好地掌握該單元的知識點，提升英語水平。值得注意的是，以上答案僅供參考，具體答案可能因版本或教材的不同而有所差異。在學習過程中，建議同學們多做練習，并結合教材認真理解相關知識點。最后，鼓勵大家在學習過程中積極思考，提高自己的英語應用能力。