【正文】
galaxy (the milky way) 3. solar system 4. star (the sun) 5. pla (the earth) 6. pla (the earth) 7. satellite (the moon) 8. et Practice: write the correct number in each box. Keys to D: 4: the Sun 2: the Milky Way 6: the Moon 5: the earth D. Write the correct number in the box ? Complete the short passage accordingly. ? Our universe is _______ up of ________, and the Milky Way is just _______ of them. Our solar system ________ of the star—the sun