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the existing steel and cast iron rods have the same diameter.considering both carrying cap
The existing steel and cast iron rods have the same diameter.Considering both carrying capacity and economic benefits,the rational selection of the two rods of the illustrated structure is().现有钢、铸铁两种棒材,其直径相同,从承载能力和经济效益两方面考虑,图示结构两杆的合理选材方案是。
A、Rod 1 is steel and rod 2 is cast iron
B、Rod 1 is cast iron and rod 2 is steel
C、Both rods are steel
D、Both rods are cast iron
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