C后半句变成主动语态为 boundaries prevent its(sound's) acoustic energy from dissipating. 变成被动语态后过去分词前省去了being---its acoustic energy (being)prevented from dissipating by boundaries...此独立主格结构在句中作状语,表示原因. 谓语动词是prevented, 省去了be的人称变化形式.
试比较过去分词结构作状语时的情况:Even if(I was) invited, i won't go. 此时可以省略主语+be的人称变化形式.独立主格结构可以看作这个形式的特殊情况,即过去分词的主语与主句的主语不一致,所以要保留分词主语.
精彩!谢谢mm哦。 结构作状语:Even if(I was) invited, i won't go. 这种情况倒是一直碰到,这个独立主格结构到还是第1次交手,不知道og里面有没有这个考点。
把这题老题顶出来,因为我现在重新看这一题,觉得E比较正确 (C) boundaries (…) prevent its acoustic energy from dissipating 逻辑似乎是错误的 我觉得是boundaries (…) dissipate its acoustic energy 逻辑比较合理, 穿过不同介质, 能量被减损(?..汗~偶没有这方面的知识)
39. For members of the seventeenth-century Ashanti nation in Africa, animal-hide shields with wooden frames were essential items of military equipment, a method to protect warriors against enemy arrows and spears.