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" />

D={(x,y),x≥0，y≥0}，[imgsrc="http://p.anan...c2081864f7c69.png"]=

已知物体的主、俯视图，左视图正确的是（ ）。 A: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/3930fea847ba4492944ddb365a59ad61.png" border="0" vspace="0" /> B: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/8c60c5d1b6634256b2ef9a91dac8488e.png" border="0" vspace="0" /> C: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/c0b01d9bd70846c0a833771f3e1329f0.png" border="0" vspace="0" /> D: <img src="http://image.zhihuishu.com/zhs/onlineexam/ueditor/201905/f4f8a566f2de4d289c53bb491395d1fe.png" border="0" vspace="0" />

=（），D满足0≤x+y≤pi，0≤x-y≤pi[imgsrc="http://...a82d9cc212b0cc.png"]

<img src="http://img1.ph.126.net/JMg9tqo6gf8sEot0y9NSUg==/6619559177490984445.gif" />? 0|<img src="http://img1.ph.126.net/uSXYTJKY1--cmM46BmL7Pg==/1177972777551495010.gif" />|<img src="http://img0.ph.126.net/-vDBDVZEQJqbFun7PrX7vg==/2887370311115280318.gif" />|<img src="http://img2.ph.126.net/NK1mnxUZa_ibCGqQvHOaoQ==/2435884448470832003.gif" />

应用归纳法，分析下图中,（）图形与众不同。[imgsrc="http://p.a...space="0"vspace="0">

设a为大于0的常数，=[imgsrc="http://p.ananas.chao...658d9486a3817d.png"]

若<img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_5e87b1af-bca5-443b-a243-291827849f02.png" />,则<img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_ad6fa5ac-dbcf-4b8b-8daa-181c5a784826.png" />的初值<img src="http://edu-image.nosdn.127.net/_PhotoUploadUtils_db6a652c-73b6-49f0-aa72-b78bfc327b03.png" />为? 0|不存在|1<br >|-1

在x=0的三阶导数为[imgsrc="http://p.ananas.chaox...725ccab7654010.png"]

设L为椭圆，周长为a，=0[imgsrc="http://p.ananas.ch...031a551e60db0b.png"]