当总应力值超过合金的（）时，铸件经产生裂纹。
A、强度极限
B、疲劳极限
C、屈服极限
D、弯曲极限
参考答案：A
15.875mm等于多少英寸？
Do you think we should ________ Bob's while we are in London?[ ]
A．call on
B．call for
C．call at
D．call upon
