退火低碳钢的拉伸曲线包括（ ）阶段。

A、弹性变形

B、<span style="FONT-FAMILY: 宋体; mso-ascii-font-family: 'Times New Roman'; mso-hansi-font-family: 'Times New Roman'">回复</span>

C、屈服

D、加工硬化

B、<span style="FONT-FAMILY: 宋体; mso-ascii-font-family: \'Times New Roman\'; mso-hansi-font-family: \'Times New Roman\'">回复</span>