应力循环的特征由参数（）来表示。
A、平均应力Sm
B、应力幅Sa
C、应力比R
D、最大应力Smax
参考答案：C
— Hello, Jack. Tracy here. It's about our ________ on Sunday morning. I'm afraid I can't make it now.
— That's OK, but you need to find another date. [ ]
A. admission
B. application
C. agreement
D. appointment
矩形花键联接采用何种基准制？其目的是什么？
