【简答题】矩形截面杆两端受载荷P作用,如图5-21所示。设杆件的横截面积为A,则下列结论中()是正确的。 1在截面m-m上的法向内力N=Pcosα。 2在截面m-m上的切向内力(剪力)Q=Psinα。 3在截面m-m上的正应力σ=P/A
sinα。 4在截面m-m上的剪应力τ=P/A
cosα。A. .①② B. ③④ C. 全对 D. 全错
【单选题】听力原文:M: Anne, are you sure you'd like to have a house in Lark Green? Don't you think it a bit too far from town? W: I'd love to live there, Jack. I think the building site there is perfect. Open count...
【单选题】Green tourism does not create green jobs, including sustainability operations, energy efficiency and renewable technologies, environmental management, natural resource conservation, smart growth, buil...