慢速英语:研究提供了关于霸王龙的新线索

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gap – n. an empty period between things happening

metabolism – n. the chemical processes by which a plant or an animal uses food and water to grow and heal and to make energy

mammal – n. a kind of animal that feeds milk to its young and that usually has hair or fur covering most of its skin

inconsistent – adj. not staying the same in quality or behavior

skull – n. the bones of the head that surround the brain