[单选题](48080)曲线上各点正矢差之代数和为零，即曲线终点的（ ）等于零。(1.0分)
A.计划正矢
B.现场正矢
C.拨量
D.正矢合计

When the time comes for anthropologists to turn their attention to the twentieth century, they will surely choose the label "Legless Man". Histories of the time will go something like this: In the twentieth century, people forgot how to use their legs. Men and women moved about in cars, buses and trains from a very early age. But ’the surprising thing is that they didn’t use their legs even when they went on holiday. They built cable railways, ski-lifts and roads to the top of every huge mountain.
The future history books might also record that we were deprived of the use of our eyes. In
ourhurry to get from one place to another, we failed to see anything on the way. Air travel gives you a bird’s eye view of the world. When you travel by car or train a blurred image of the country- side constantly smears the windows. Car drivers, in particular, are forever obsessed with the urge to go on and on: they never want to stop.

A. Legs become weaker.
B. Modem means of transportation make the world a small place.
C. There is no need to use eyes.
D. The best way to travel is on foot.