Dinosaur scientists can probably know whether dinosaurs were good parents by __________ .

• A、watching many kinds of animals 

• B、studying dinosaurs' living relatives

• C、following the tracks left behind

• D、working on dug-out dinosaur eggs

Hunger is caused by __________.

• A、too much food and water in the body 

• B、a lack of oxygen in the blood

• C、seeing or thinking about food 

• D、a lack of certain chemicals in the blood

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