用一个表达式写出下图中所示电压U的数学函数表达式为（ ）。http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/f30c66693b6344938cfe0e78097223af.png
举一反三
- 用一个表达式写出下图中所示电压U的数学函数表达式为（ ）。[img=218x106]17a3dd42005a264.png[/img]
- 用一个表达式写出下图中所示电压U的数学函数表达式为（ ）。[img=218x106]17869e9c5d33ed0.png[/img] A: ε(t-1)- ε(t-2) B: 2ε(t-1)- ε(t-2) C: ε(t-1)- 2ε(t-2) D: ε(t-1)+ε(t-2)
- 下列表达式中写法错误的是（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/31bde206234643918287051fe28c4e0b.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/15084217534b4cb3b781b39f8e5173c5.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/2a4e96f210584cf9ba186bc6333bc03a.png" />
- 主视图是半剖视图，表达正确的一组是（）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/91a7aa656cee4f2dbc2d22fc7c61a7b9.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/73d7ce95bdec4beeb502d7c4332df823.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/d0de6ded70094a3d9613087b840a3c19.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/8250cbe6f2f54332ae2a27ded3de53ae.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" />