若x2+y2=1，则dy为（ ）
A:
B:
C:
D:
A:
B:
C:
D:
举一反三
- 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" />
- 与y=x是同一个函数的是（ ） A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/f86ae5251f654e2883551f545dfe08e7.png"> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/9423178e08ad4e9dbdc9367e98a5ef51.png"> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/cdc5f4144cbb469ab64328415e12a732.png"> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/c040b4fc143f484587591e1bb39b7dfc.png">
- 下列情况中，会产生感应电流的有： A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/1e2e7b8e99294e8a824d5906dda51113.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/6081bc4ae79e452d904680d64f32af5a.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/655e36b2c61547b09b3411739b7ad3be.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/2735a230795a4cbda1a0197612327818.png" />
- 下列函数中不是复合函数的是（ ） A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/852398e68ff74631bd3a10e9b908904b.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/b2421a13aeb94b93b18f4e7a67c2630f.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/f8c9b5fc3bc24e378a5013539240f424.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/78be77e785734fecbef1cc7dec213352.png" />
- Photoshop中，图像的透明部分会表示为（ ） A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/4e20cc22fa2d419b927fba9a72c9da1b.jpg" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/fe4f3b584da94076a934d71eb300a12a.jpg" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/a6f4e75987e54a8399f598f3eef69516.jpg" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/777cf882eb0e439b80358516831b1526.jpg" />