水的质量流量为30t/h，温度为90℃，如管道内的平均流速为4.4m/s，则管道的内径为（）mm

层流时，管内平均流速是最大流速的___倍（） 湍流时，管内平均流速约是最大流速的___倍（） It’s suggested that some activities to celebrate the 30th anniversary of the Reform and Opening-up. The 30th Olympic Games, ______ between July 27 and August 12 in 2012, will take place in London[ ] What advantages do you think London ________other cities in hosting the 30th Olympic Games? It was July 24th when he arrived in London, ______ the 30th Olympic Games would be declared open 3 days later. The 30th Olympic Games, _______ between July 27 and August 12 in 2012, will take place in London. How long will it be ________ the 30th Olympic Games is held in London? —It won’t be two years, I think The moment the people of London heard that their city had won the bid for the 30th Olympic Games, they ________ cheers. Lucy was born ______ January 30th, 1998, when her sister got married ______ a fashion designer. On May 30th, 2005, one bowl in the Ming dynasty(朝代)________at the price of 30.36 million Hongkong dollars. （）According to the terms of the contract, the shipment is to be effected by 20 July and we have the B/L by the 30th at the latest. The 30th Olympic Games, officially_________as”London 2012 Olympic Games”, will take placefrom July 27 to August 12 [ ] 按《JGJ/T132-2009居住建筑节能检测标准》要求，在检测室内平均温度时，室内平均温度检测数据记录时间间隔不宜超过30min（） 在检测室内平均温度时，室内平均温度检测数据记录时间间隔满足要求的是（） I spent _______ awful holiday this summer because _______ big flood on July 30th made lots of people lose lives. 在检测室内平均温度时，下面室内平均温度的检测持续时间不正确的是（） 流量与流速的关系：V=uA，G=（）。其中V为体积流量，u为流速，A为管道的截面积，G为质量流量，ρ为流体密度。 流量与流速的关系：V=uA，G=（）。其中V为体积流量，u为流速，A为管道的截面积，G为质量流量，ρ为流体密度 某管中流体流动速度为1.2米/秒，如流量加倍，管道中流速为（）