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o 3. yet 4. just / already 5. already Ⅱ. 1 5 DAEBC Ⅲ. 1. to imagine 2. have lived 3. haven’t been 4. that 5. hobbies 。 What will our life be like by the year 2100? It’s difficult for us (1) (imagine). People (2) (live) on the earth for so many years. It is being more and more crowded and polluted. Maybe people will live on the other pla— Mars. Astronauts (3) (not be) to Mars yet so far. Let’s imagine what our life will be like on M