单项选择题
A.一个B.二个C.三个D.四个
A.热切B.冷切C.变形D.裂纹
A.24mm,22mmB.24mm,23mmC.24mm,24mmD.22mm,23mm
A.30mm,20mmB.30mm,15mmC.25mm,10mmD.30mm,10mm
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