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【单选题】
单位产品成本与其产量的相关、单位产品成本与单位产品原材料消耗量的相关( )。A.
两者都是正相关
B.
两者都是负相关
C.
前者是正相关，后者是负相关
D.
前者是负相关，后者是正相关
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【单选题】根据物质流动是否主要由人类活动引起可分成（ ）两类The material flow can be divided into the following（ ）two categories according to whether the material flow is mainly caused by human activity
A.
物质生物地球化学流动和人为流动 Material biogeochemical flow and its anthropogenic cycle
B.
物质随大气流动和随水体流动 Material flowing with the atmosphere and with the water body
C.
物质工业流动和农业流动 Material industrial and agricultural flows
D.
物质产业流动和消费流动 Material industry flow and consumption flow
【单选题】The de Broglie wavelength of an electron with kinetic energy of 100 keV is ( )
A.
3.702 pm
B.
3.702 nm
C.
3.702 fm
D.
3.702 mm
【单选题】It has been predicted that AI can replace human in every activity in ________.
A.
2021
B.
2031
C.
2051
D.
2061
【单选题】A rise in human sympathetic vasomotor fibre activity
A.
enhances local blood flow through a tissue
B.
increases the capillary filtration rate
C.
can raise arterial blood pressure
【单选题】The wavelength of an electron whose velocity is 1.7 × 10 4 m/s and whose mass is 9.1 × 10 -28 g is __________ m.
A.
4.3 × 10 -11
B.
12
C.
4.3 × 10 -8
D.
2.3 × 10 7
E.
2.3 × 10 -7
【单选题】Packaging is an activity closely associated with the revolution of society and , can be __ to human beginning .
A.
traced back
B.
come back
C.
tracked back
D.
gone back
【单选题】The average wavelength of visible light is2,000 times ______ the diameter of an atom.
A.
much as
B.
as great
C.
greater than
D.
more than that
【单选题】The wavelength of a standing wave in an open basin is ( ) the length of the basin.
A.
'1/2
B.
'1/3
C.
'3/4
D.
'1/4
E.
'2/3
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