A、B、C皆错在句子重心问题 “ Prospecting for gold during the California gold rush was a relatively easy task” 的原因不是"erosion, prehistoric glacier movement, and ancient, gold-bearing riverbeds "这三个名词 而应该是“erosion, prehistoric glacier movement, and ancient, gold-bearing riverbeds put gold literally within reach of anybody with a pan or shovel.”这句话
选项E: Since A, B, C put gold literally within reach of… 选项A: because of A, B, C put gold literally within reach of… 选型B: because of A, B, C ,and putting gold literally within reach of… 选型Cwing to A, B, C ,and putting gold literally within reach of… 选型D: since A, B, C , putting gold literally within reach of…
the structure of the clause: subject: erosion,prehistoric glacier movement,and ancient, gold -bearing riverbeds ancient, gold-bearing both modify riverbeds thrust to the surface by volcanic activity modifies riverbeds too verb:put