变量泵系统,快进和快退时()。 A: 溢流阀阀口关闭，不溢流 B: 溢流阀阀口打开，溢流 C: 溢流调压 D: 安全保护

上图中阀11为机动换向阀，主要作用是通过阀芯换向，控制油路中油液的流动方向。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/d59717e9731843d3b4bc58ab27d3e5da.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" />

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" />

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" />