Điền từ còn thiếu trong đoạn văn sau : Our planet... is revoling around the sun, which is a fairly small and ordinary star. There are about 250 billion stars in our galaxy, and billions of galaxies in the... In recent years, scientist have sơm scientist believe that there may be large numbers of stars with their own planets. It is almost impossible to reach the stars in the Milky Way galaxy. It would take the fastest Earth... about 40,000 years to reach the... star, all the time. Các từ còn thiếu : 1. Earth 2. Spaceship 3. Universe 4. Nearest 5. Intelligent