1. This is____useful book. I"ve read it for hour. 2. _____elephant is much heavier than ____horse. 3. _____doctor told him to take______medicine three times____day. 4. Let"s go out for _____walk. 5. There is____woman over there.____woman is Meimei"s mother. 6. ____sun rises in_______east. 7. ______Changjiang River is______longest river in_______China. 8. Are you going to do it____second time?