http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/44f4d22711964c23980340adb7809625.pnghttp://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/3d4966e983de4b688abd5941e42a0548.png

设http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/5f9f81d9a1184c2eb383cb81ebbe2768.png，若http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/410a0d9f8b4a4f82a6818a45f4a3b450.png，http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/637f75734cb849caa773da5377f55f5e.png，http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/29aefd40f6c54e788587a2115dd02467.png，则http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/631634fcf7854ec88eedede14de7c1de.png之间的大小顺序为（ &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;）<br>

设http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/6e6de13adf014e1f9fdc7954cb313377.png是由方程http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/6d1ea7ec74bb4607aee50aa325108197.png确定，求http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/1d60e0ceb7d14d26a00863c192e0bbf3.png（&nbsp; &nbsp; ）

图示应力圆对应于应力状态<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/a61d48f304e9454fb6f3d8fcac0a5888.png" /> A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/fa83fd043ee946869755b338236b2b0e.png" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/77ff74928a3642928e805440db706068.png" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/6cce8e25b7ec4d00895cd86fabc16f64.png" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/62d9a4357886450cbfb0bde0deda67ec.png" />

设http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/90c19a717ac34717836dbca4afba1bd9.png是由方程http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/7648e783c2f24044bb84346d0e07e161.png确定，求http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/d24ed3aef9a94d38965289947da528f7.png（&nbsp; &nbsp; &nbsp;）

已知向量的两个方向余弦分别为，则向量的单位向量为 。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/ddccbadd28ff4393bdbc528098c1dc43.pnghttp://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/7904ae829dab4b16ad7979ea93482956.pnghttp://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/4c2541850dba41bbaf0047a783702fb8.png

设积分区域D由http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/0c9ae1ed54164a58bd49dd327b8b9613.png和http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/106bacc400de4a258c3c2cc1e88f5e50.png围成，则http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/533bf3bfe8d7439fbe2689a974be1cf1.png（&nbsp; &nbsp; ）<br>

设函数http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/2483d32f49ee48579b3a0f795ffeb08e.png，则http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/a038cd64e1d845ebb5779107a4d344a1.png（&nbsp; &nbsp; ）

在纯电感电路中，电压应为（）。 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/fe9a2726638343cf8f66ce58ca5146cc.png"> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/0f360aa88e6d4c1993733df279cd3734.png"> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/08dcf081ff844b1e92735fc0b9d1a227.png"> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/344144b6bd8f4089899e73bd6daadc00.png">

欠阻尼二阶系统的闭环极点分布图为（ ）。 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/e26de5d73f984ba391a6ac30d8c6d4fe.png" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/11aa916316d34c4eb0ae8cafd3bdaeb0.png" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/31e7b12aeb2e427f882a4b430c6f6d94.png" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/aa587a3419434ed38f3114ee0eeaba96.png" />