防止裂纹的措施?
参考答案:
1.增加净水压力。
2.选择和控制合适的变形温度和变形速度。
3.采取中间退火,以消除变形过程中的硬化,变形不均匀,残余应力等。
4.提高材料质量。
a,b,c是直线,且a⊥b,c⊥b,则a与c的位置关系是______.
—May I come in? I’m sorry I’m late.
— Come in, please. But could you please tell me _______________?
A.why you are late again
B.what were you doing then
C.who you talked with
D.how do you come to school