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A major source of rock salt is domes, of rock salt embedded in surrounding layerof earth
(a)are that vertical cylinders (b)that vertical cylinders
(c)cylinders are vertical (d)vertical cylinders
答案是d 谁可以给我讲一下,还有这里前后两句是什么关系,同为语吗?
Hot springs are one of the most characteritic features of areas of recent volcanic activity, although in other areas less abundantly.
(a)also to have occured (b)their occurrence also
(c) also occur (d)they do also occur
答案是d为什么,还有b为什么不对
请大家帮我讲一下,谢谢 |