VOA慢速英语:研究称食草恐龙到达北半球的时间较晚

hemisphere -- n. a half of the Earth

sheet -- n. a wide, flat surface or area of something

pole – n. either end of the imaginary line around which something (such as the earth) turns

magnetism –n. the property of attracting certain metals : the attracting property of a magnet

cool –adj. appealing, approved of