使用蒸汽压力的高低对系统的真空无影响。
参考答案：错
At a college football game,
of the seats in the lower deck of the stadium were sold. If
of all the seating in the stadium is located in the lower deck, and if
of all the seats in the stadium were sold, what fraction of the unsold seats in the stadium were in the lower deck
某次军事演习中，一架无人机停在空中对三个地面目标点进行侦察。已知三个目标点在地面上的连线为直角三角形，两个点之间的最远距离为600米。问无人机与三个点同时保持500米距离时，其飞行高度为（）米？
A.500
B.600
C.300
D.400
of the seats in the lower deck of the stadium were sold. If 
of all the seating in the stadium is located in the lower deck, and if 
of all the seats in the stadium were sold, what fraction of the unsold seats in the stadium were in the lower deck