已知<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/43114282e941476ba93775909fb3f237.png"/>，用拉氏变换法求解微分方程<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/0db291610cb64fa8ad46ae0bd15476b0.png"/> 的结果为（ ） A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/29ff68f02bdd438bb2e16c2a6e1ec18b.png"/> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/0010c1593c9145a4b928548ab38cf426.png"/> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/1f562f2536584121b53c30e4db08df88.png"/> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/f593399cb630435192baa8b3e871b533.png"/>

一质点在平面上作一般曲线运动，其瞬时速度为<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201707/cd2c54e096b2475db8bcecd84e554eb0.png" />，瞬时速率为<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201707/359eb2c648264727bd0a2bc72d54b233.png" />，某一时间内的平均速度为<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201707/32268b5fc5bc43619f3bb1de9c43715b.png" />，平均速率为<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201707/99f1a21b975449648922aab0accdc025.png" />，它们之间的关系必定有（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201707/27daf7237fe740349eb8756c75d23df6.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201707/f2f418f88e564f8c9d46babbe9bc612b.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201707/5d84042638794095a9b9e7760b0cbb53.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201707/cd811196b38f419c82b27356c7d84ca9.png" />

What are the comedies of Shakespeare? A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/1882addb95d34f3e877db8ec62e82507.png"/> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/4e230d2e03cc46c2b717155e90fdd081.png"/> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/7f4368645eff4e4b9ec89b237843dabd.png"/> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201901/5ccbfc9718084d318abfbbe254ae048b.png"/>

已知系统和初始条件<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/15eb73651c0a4ae094e6de902b6c21ca.png" />求初始状态激励的响应 ( )。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/d016acd038b04b699e76c2354357c3d2.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/7a10be8f1ce74599a610fd0b9b9eb195.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/4621f442538946fdb897b89a1461e1e1.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201902/61b797beffc74a99b91e1934af1372fb.png" />

对于正序的对称三相电源，已知<img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/d469ef1a00bf4a7b9f72206db92b2722.png" />则（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/f46f01b8a0944bf5b97b3085df4963af.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/bdc84f660db9480893ab3eb3df8c9174.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/2419acedbbc14be7b11bb6e2cb005039.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/6fabd0d71b0344b68b86a539fd0e0c9e.png" />