preposition is a word or group of words such as in, from ,to and out of, used before a noun or pronoun to show place ,position,time or method。
介词一般放在名词或代词之前,只表示其后的名词或相当于名词的词语与其它句子成分的关系。如:in ,from, to ,out of,
conjunction is a word that join words ohrase, or sentences
连词是连接单词,短语,从句,分句或句子的一种虚词,在句中不单独做句子成分。
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