acting against the lower surfaces sufficient to counteract their weight. 某些物体漂浮在水面上或其他液面上,这一现象也表明,存在着一个作用在物体底部表面的力,该力足以抵消物体的重量。(The fact that... , that 引出的是同位语从句。 There exists ...属于 there be 的句型。这种句型都是倒装结构, 主语是 force ,谓语是 exists 。分词短语 acting ... weight 作定语,修饰 force 。 sufficient .。. weight 是形容词短语, 也修饰 force 。) 14. It was postulated in the early days of the subject that electricity was a fluid or rather two fluids, present in equal quantities inside matter and that charging a body consisted of adding an excess of positive of negative fluid to it. 在这门学科的发展早期曾经假设过:电流是一种流体,或确切地说是两股流体,这两股流体等量地存在于物体中,同时还假设,给物体充电就是给该物体加过量的正电流或负电流。(present ... matter 是形容词短语,但前面有逗号,因此是非限定性定语,修饰 two fluids 。) 15. For very many years London has been a business centre with hotel modation mainly for visiting businessmen
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