原罪
资本成本率有下列种类：（）。 ["个别资本成本率","综合资本成本率","加权资本成本率","边际资本成本率"]
如何通过相互学习加深学习？
先定
Which statement is true about Foreign Exchange Station （FXS） ports on a router？（） ["The FXS interface allows an analog connection to be directed at the public switched telephone network （PSTN’s） central office.","The FXS interface connects directly to a standard telephone，fax machine，or similar device and supplies ring，voltage，and dial tone.","The FXS interface connects directly to an IP phone and supplies ring，voltage，and dial tone.","The FXS interface connects directly to ISDN voice channels."]
何为加工硬化？列出产生加工硬化的各种可能机制。（不必说明），加工硬化现象在工业上有哪些作用？
