压力容器用钢材的塑性指延伸率（δ）和断面收缩率（Ψ）。它表示金属材料在受力条件下塑性变形的能力。其值是表示试样受拉力状态时的塑性变形能力。
参考答案：对
--Is it convenient to you if I pay a visit to you at 10:00 tomorrow morning?
--I' m afraid not. I _____ a lecture then.
A．will have given
B．am about to give
C．will be giving
D．was giving
A．+→
B．→+
C．+→
D．→+
+
→
→
+
→
→
+
