组合梁如图示。已知q=2kN/m ， F=10kN , 求固定端 A 处的约束力偶 M A 等于 。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201805/3dc88c1d09c94a299948b91b63cfed38.png

当_____时，大气气团处于稳定状态。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201705/cfd65918697d4e5aac32ffa652eeeb44.png"> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201705/3627620c7b20481c9fd4d9816cbe61d3.png"> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201705/da408a1038da41b2a6f4022dd469857f.png"> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201705/50437c56e4e340e59d42b59bc26d9802.png">

悬臂梁如图所示。加载次序有下述三种方式：第一种为F、Me同时按比例施加；第二种为先加F、后加Me；第三种为先加Me、后加F；在线弹性范围内它们的应变能为（ ）。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201811/64e20d7079de41ea8ae154372d727057.png

图示曲柄连杆机构，已知曲柄OA长L，重量不计，连杆AB长2L，重P，受矩为M的力偶和水平力Ｆ的作用，在图示位置平衡。若用虚位移原理求解，则必要的虚位移之间的关系为___________，力F的大小为_____________________。<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/be06434307bd424abfc4ebfe02661f7a.png" /> A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/b8e7b964d1c84aeca7b22ddef4de87a2.png" />;<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/a584946cde17410c945d6611ff2113b5.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/1aaef24e28ee477ab25dae0a400bf23f.png" />;<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/f3b395453e1d48bdadff2e37dfbbb626.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/be37912822f0451bb15639b7fa0589f1.png" />;<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/6d1112b5c1b4446b93578138388ed79f.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/89b7bcef6b51410cb624a654747d56ee.png" />;<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/0e2b78f437914a1eb8327d13185eaedf.png" />

梁在集中力偶作用的截面处，它的内力图 （ ）。 A: F图突变、M图无变化 B: F图突变、M图转折 C: M图突变、F图转折 D: M图突变、F图无变化