【单选题】以下说法中正确的是:()(1)脆性材料只发生断裂失效,塑性材料只发生屈服失效;(2)材料中危险点的应力状态与材料的破坏形式有关;(3)对四个常用的强度理论,其各个相当应力的计算表达式中,全部三个主应力都用到的是第二和第四强度理论。
【单选题】在第五肋间隙,当乳头直下,前正中线旁开4寸穴位是
【单选题】The 18th century witnessed a new literary form--the modern English novel, which is contrary to the medieval romance, gives a ______, presentation of life of the common people.
【单选题】What you have done is _____ the doctor's orders.