图示单元体，属于何种应力状态，有四种描述，正确的是（）。https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/80ae893b26fd4ebb9496edb090b5cc2b.png
举一反三
- 历史曲线构件的图标是( )。 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/dfb6b619f35547c590f6e6c6aab95b3f.png" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/e7e0aaa5f6e84ba89410cc93b06a451a.png" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/354425393230484ab64d64a718bd9bad.png" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/1f794e99ed004e3190fa5181c32fe4e8.png" />
- 下列方程所描述的系统中（ ）是线性时不变系统。 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/5740348e23d246eebda0442284882d6d.png"/> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/87c5df9c28f54b398bbedc5da45e7a02.png"/> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/ece1036e5a3c410e8f8b3de147910c04.png"/> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/69fc98a558ce4f3eb743c68be74cf923.png"/>
- 图示各杆BC段为轴向拉伸（压缩）的是（ ） A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/412a1c88a2924281a60f66b253c86c67.png"> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/7ef22ac8d02b49db8625a91064e510ef.png"> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/23a086371806496786bdb9d1789a098d.png">
- 下面的表达式中，正确有？ A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/0e169fdf5e354dd4af80ea6386ddeca5.png"/> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/5124889b558b4186ba4140ca7692d717.png"/> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/f3d2d0d80b744f74899371cae0395a71.png"/> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/2af6ef9203e94ea2b993e1ad4d99e5d2.png"/>
- 等直杆两端受轴向载荷作用，其横截面面积为A，则n-n斜截面上的正应力和切应力为（ ）。<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/34249dc5abdf4bb58b66acf0a0cb0ad2.png" /> A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/b50ab54430864d76a6693093f6af1eb9.png" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/9654a98c09d14085a3426eee7fbdac20.png" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/584a8c558db14b57ba94de20ec833b53.png" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201911/c99c6d995f8046ec867195b44e2ea247.png" />