钢板的弯曲为了不影响其力学性能，通常当（）时必须热弯。
A.D/s＞40
B.D/s=40
C.D/s＜40
D.D/s＞20
参考答案：A
--- You’d better not buy a house these days.
--- ___________. I think it’s a good time.
A．What’s the matter?
B．Probably you are right.
C．Sounds reasonable!
D．What about you?
Walsh函数具有理想的（）特性。
