已知物体的主、俯视图，左视图正确的是（ ）。
A:
B:
C:
D:
A:
B:
C:
D:
举一反三
- 下列化合物有旋光性的是( )。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201907/42754375451947b4a2097a204914e285.png" border="0" vspace="0" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201907/259cc0f9369441888e4306c19039152f.png" border="0" vspace="0" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201907/c6798f5eb7e14df7a79f40cdd7d2f42e.png" border="0" vspace="0" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201907/4275928f484d4bad94705297fe159cf0.png" border="0" vspace="0" />
- 下列草图用旋转特征工具不能生成实体的是（）。1、<img width="50" height="100" src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/0c0ba8db9acf4933a0e5df79d9dddaea.png" border="0" vspace="0 2、<img width="60" height="100" src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/341180a27efb4211b512ab4269ae865a.png" border="0" vspace="0 3、<img width="80" height="100" src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/97007edcda2644d78d09b1089aa9af7a.png" border="0" vspace="0 4、<img width="80" height="100" src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201908/6a56890b40874f78a8df75419e014d27.png" border="0" vspace="0
- 由角系数性质，任意两表面间的角系数有下列关系（）。 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/8fe9f71498f04232b7d9626ea192f5d5.png" border="0" vspace="0" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/d2b63ba506614bfab0e0d91b5a62b9bd.png" border="0" vspace="0" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/f88fb5553ef147e996473ea8d738144e.png" border="0" vspace="0" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/3bb42a34fc7943abb899e6ad38246778.png" border="0" vspace="0" />
- 如图所示，离心机通风机借集流器从大气中吸入空气。若插入盛水容器的玻璃管中的水上升高度为h，则通风机流量<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/b90be52d519d4880a560e59df52dd29c.png" />=（）。<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/dca2260bbd5c4051b28bbb87ae1d6de9.png" /> A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/7b4225635cfe41e28af202418785be8d.png" border="0" vspace="0" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/05404534275442c597194a44ee9f46f7.png" border="0" vspace="0" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/5509cc1799e54c64a7a11a7f37417710.png" border="0" vspace="0" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/307ded8ddb2c486d935b6bc79faa7688.png" border="0" vspace="0" />
- 若x2+y2=1，则dy为（ ） A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/d045b5f235a54083ab91e6f717cf00d8.png" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/74173c5355234874ab8cb9275865d5d6.png" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/bbfb37ba58fc4de0aa8688e0bb53cef5.png" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/f9a206c25e8c4ea1bd7b51519afd76b7.png" />