--- Miss Lee, I didn’t catch what you said just now. Could you tell me ___________ again?

---OK.

A．what should we take

B．where shall we meet

C．when we would start

D．how we will get there

材料在外力作用下变形，当外力取消后能完全恢复原来形状的性质称为（）。

A、刚性

B、塑性

C、半刚性

D、耐久性