如图示并联管路，已知各支路的沿程阻力系数之比为<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/6e209020d20f4543823ce6516ae8ca06.png" />，管长之比为<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/50814fe028094040bc955d8e1542b6d2.png" />，且<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/40b4c6a9565b483590c5c7d607e7ed66.png" />，则两支管的流量之比<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/1055534bfce6426a94682ba086a5b17e.png" />=（）。<img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/77815369f5cd41f3a2e68b9524b454c5.png" /> A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/0cd231eebe45465f941a0f614743e6d2.png" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/7555afa5223e40bf89ca575cf7b52754.png" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/1b06cd474b844644a6d97ad87d208e94.png" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/d0b2bca045414236a7d1c9925a9264f2.png" />

下列积分中等于零的是 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/beafcd1bd9a045e4bef379cba1d6c572.png" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/fc2d4b861cbf43eb8a27dde67b97f680.png" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/d9c33bed53f147c4b62a3f7553d496e0.png" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/4e50aaa9bf42400db5b7573935fc97e4.png" />

剖视图正确的画法是 。 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/9537d515da014e68a3d3cb450f99ad38.png"> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/1a23c24f84774377874f0c38fd153a7e.png"> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/f5954dedb8bd4b788a4a43c7a11266a7.png"> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/bd015ac5086848d3876260b7aaf6bfc5.png">

下列各表达式正确的是（）。 A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/c00e74606aff46b3bd686c1cbb405da6.gif" /> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/a9452605ec5b4dfc8fede5ae6baae903.gif" /> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/316677d9b4fe41d09b0ef5f8b18e4a0b.gif" /> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/1d4a5808f5524820897bf23dd439ad0c.gif" />

下列命名正确的是( ) A: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/45d758d675564df2b279142c14ae9e2e.png"> B: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/4889492bf6634f04b7c4e5c944f66ed8.png"> C: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/70bc128530144f07aa006af0ebe6a989.png"> D: <img src="https://image.zhihuishu.com/zhs/onlineexam/ueditor/201909/ddcdceddcb9a49bf8ab24aea015a7a9a.png">