【正文】 用條件下。s ancient indigenous religion, while Du jiang yan is c onsidered to be the oldest functioning watercontrol project in the world. Chengdu ranked third in tourist facilities, management and services among 60 Chinese cities in a customer satisfaction survey released last year. But, Li added that efforts are still needed to develop more tourism products, improve English services and provide accurate translation of traffic signs and scenic billboards. Zhao Yun, chairwoman of British Chamber of Commerce Southwest China, told China Daily that his colleagues found the policy very convenient. A British client once flew here and stayed for just one day to check her ordered goods, she said. Zhao was born in Shanxi province, but she has lived in Chengdu for more than 10 years. My life was like a running race moving from place to place. I also lived in Beijing and Shanghai before, she said. But Chengdu is a place that you never want to leave once settling do wn. It is now my second hometown, she said. If the environment is further improved, the city will attract more people to visit and live, with the 72hour visafree policy and pelling conditions in transportation, culture, climate and cuisine, he said. Foreigners also gave positive feedback on the policy. A spokesman from Dell Inc said the pany has a global hub of operation in Chengdu, so the threeday visa has an immediate and positive influence on the pany39。 Visafree policy brings Chengdu biz, tourism boost. Making national headlines several times, Chengdu39。 答： ① 過水?dāng)嗝婷?積 A，水深 h，沿程改變。對(duì)于漸變流，過流斷面上動(dòng)水壓強(qiáng)分布符合靜水壓強(qiáng)分布規(guī)律 ( √ ) 5．壁面粗糙的管道一定是水力粗糙管。 2．判斷層流和紊流的臨界雷諾數(shù)是 (下臨界雷諾數(shù) ) 3．圓管的水力半徑為 4d 二、判斷題 。 （ ） 。（ 正確 ） 4．阻力平方區(qū)內(nèi)阻力系數(shù)與雷諾數(shù)無關(guān)。 (4)必須為