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單項選擇題

碳素鋼中含碳量（）為中碳鋼。

A.0.22％
B.0.42％
C.0.62％
D.0.82％

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單項選擇題

鋼材是以（）為主要元素，并含有其他元素的合金材料。

A.碳
B.鐵
C.磷
D.錳

單項選擇題

連續(xù)梁、板的受力特點是（）。

A.跨中正彎矩，支座負彎矩
B.跨中正彎矩，支座正彎矩
C.跨中負彎矩，支座正彎矩
D.跨中負彎矩，支座負彎矩

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