点击下方单词,选择对的这个单词
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1. 不明飞行物A UFO is an object seen in the sky or landing on earth which cannot be identified and which is often believed to be from another planet. UFO is an abbreviation for (缩略=) 'unidentified flying object'.
多通过句子记忆单词，而不是单独死记硬背。
