某一色谱柱从理论上计算得到的理论塔板数 n很大,塔板高度H很小,但实际上分离效果却很差,试分析原因
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He still remembers being taken to Shanghai when he was very young.()
Fill in each blank with the proper form of the word given in brackets. 1.() _________ a mystery, much like Edgar Allan Poe himself.
能吸引 金属或它们的 的性质称为磁性,具有磁性的物体叫磁体
磁体有两个磁极,它们分别叫______、______.同名磁极______,异名磁极______.磁体周围存在______.磁体有两个磁极,它们分别叫______、______.同名磁极______,异名磁极______.磁体周围存在______.