部属各高等学校适当推迟2020年春季学期开学时间,具体开学时间与当地高校开学时间保持一致,并报教育部备案。春节返乡学生未经学校批准()提前返校
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A.春季凉爽比较湿润,气温下降快
B. 冬季降水较少,气温回升快而不稳定,多风沙天气
C. 关中及陕北大部属暖温带气候
D. 陕南属北亚热带气候
(清华大学2006--2007学年春季学期期中考试试题)The period of oscillation T of a water surface wave is assumed to be a function of density p,wavelengthλ,depth h,gravity g,and surface tension 7.Rewrite this relationship in dimensionless form.What results if γis negligible?
(清华大学2006--2007学年春季学期期中考试试题)A fireboat-pump delivers water to a vertical nozzle with a 3:1 diameter ratio,as in Fig.6-38.If friction is neglected and the flow rate is 0.02 m3/s,how high will the outlet water jet rise?
(清华大学2006--2007学年春季学期期中考试试题)On a sea-level standard day,a pressure gage,moored below the surface of the ocean(SG=1.025),reads an absolute pressure of 1.5 MPa.How deep is the instrument?
(清华大学2006--2007学年春季学期期中考试试题)Consider incompressible flow in the entrance of a circular tube,as in Fig.6-39.The inlet flow is uniform,u1=U0.The flow at section 2 is developed pipe flow.Find the wall drag force F as a function of(p1,p2,ρ,Uo,R)if the flow at section 2 is: