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【简答题】
2003年10月15日9，我国自行研制的“神州五号”载人飞船，在酒泉卫星发射中心发射成功，准确进入预定轨道，中国首位航天员被顺利送上太空，并于次日6时左右成功返回；中国成为继前苏联、美国之后的第三个独立进行载人航天的国家。 （1）火箭在发射时尾部的火焰如果直接喷到发射台，发射架要熔化，为了保护发射架，就在发射台底建了一个大水池，让火焰喷到水池中，这是____________，使围环境温度不致太高。 （2）火箭的上升是靠三台主发动机和置于大燃料箱两旁的两台火箭助推器实现升空的，当火箭上升到大约55km的高空时，两台助推器燃烧完毕，会自动脱落，助推器在脱落之前，它相对___________是静止的。 （3）飞船进入运行轨道后，在距地350km的高空作圆运动，飞船平均1.5h可绕地一，飞船的运行速度约是________km/h。（地球的半径约为6400km）
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举一反三
【单选题】When the present value of the cash inflows exceeds the initial cost of a project, then the project should be:
A.
accepted because the internal rate of return is positive.
B.
accepted because the profitability index is greater than 1.
C.
accepted because the profitability index is negative.
D.
rejected because the internal rate of return is negative.
【单选题】Before a project can be planned, ( ) should be established.
A.
estimates of the cost
B.
product objectives and scope
C.
an effective assessment of risk
D.
a realistic breakdown of project tasks
【单选题】以下哪种说法错误
A.
神经损伤特征表现为腕下垂
B.
尺神经损伤特征表现为爪形手
C.
正中神经损伤特征表现为猿手
D.
肘关节后脱位特征表现为成角畸形
E.
Colles骨折特征表现为餐叉样畸形
【单选题】When the present value of the cash inflows exceeds the initial cost of a project, then the project should be:
A.
accepted because the internal rate of return is positive.
B.
rejected because the net present value is negative.
C.
rejected because the internal rate of return is negative.
D.
accepted because the profitability index is negative.
E.
accepted because the profitability index is greater than 1.
【单选题】以下哪种说法错误()
A.
桡神经损伤--腕下垂
B.
正中神经损伤--'猿'手
C.
尺神经损伤--爪形手
D.
肘关节后脱位--成角畸形
E.
Colles骨折--餐叉样畸形
【单选题】When the present value of the cash inflows exceeds the initial cost of a project, then the project should be:
A.
accepted because the internal rate of return is positive.
B.
accepted because the profitability index is greater than 1.
C.
accepted because the profitability index is negative.
D.
rejected because the net present value is negative.
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