Which of the following perks is out-of-date today?
A. a workshop on the recent stock market.
B. an expensive car room that can be used at a relatively low rent.
C. a vacation to a beautiful scenic spot for relaxation.
D. a training on the expertise which may lead to promotion in career.
与基本分析相比,技术分析对市场的反映比较直观,分析结论时效性较强。 ()
A. 正确
B. 错误
A research scientist wants to study a certain attribute of dogs. It is estimated that approximately 5 percent of all dogs have this attribute. If the scientist wants to study a sample of N dogs having the attribute, approximately how many dogs should be screened in order to obtain the desired sample size?
A. N/5.
B. 5N.
C. 20N.
D. 105N.
E. 120N.
假定AB跨(即左端边跨)按荷载效应标准组合并考虑长期作用影响的跨中最大弯矩截面的刚度和B支座处的刚度,依次分别为召B1=8.0×1013N.mm2,B2=6.0×1013N.mm2;作用在梁上的永久荷载标准值qGk=20kN/m,可变荷载标准值qQk=30kN/m。试问, AB跨中点处的挠度值f(mm),应与下列何项数值最为接近?
提示:在不同荷载分布作用下,AB跨中点挠度计算式如图4-3。
A. 20.5
B. 22.6
C. 30.4
D. 34.5