1、
History is not only the time passed, but also full of mistery and unknowns.
历史之于人们既是真实存在的过去，又充满着神秘和未知。
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2、
3、
Gowaty agreed that exceptions to Darwin's theory exist and that there are many unknowns.
拉夫加登说:[人们知道,动物多常将性行为视为纯粹社交,以及多少物种的性别角色逆转,使得雄性肤色单调无趣、性色彩斑斓以竞争雄性目光的时候,人们经常大惊失色.
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4、
Before his remarks , the president laid a wreath at the tomb of the unknowns.
在演说之前, 总统向无名烈士墓敬献了花环.
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