求助月度狗喜马拉雅那个题

demonada

V1  【by: arieslee0410】

In 1975 Chinese survey teams remeasured Mount Everest, the highest of the Himalayan mountains. Like the Britishin 1852, they used the age-old technique of “carrying in” sea level: surveyorsmarched inland from the coast for thousands of miles, stopping at increments ofas little as a few feet to measure their elevation, and marking each incrementwith two poles. To measure the difference in elevation between poles, surveyorsused an optical level—a telescope on a level base—placed halfway between thepoles. They sighted each pole, reading off measurements that were then used tocalculate the change in elevation over each increment. In sight of the peaksthe used theodolites telescopes for measuring vertical and horizontal angles—todetermine the elevation of the summit.

TheChinese, however, made efforts to correct for the errors that had plagued theBritish. One source of error is refraction, the bendingof light beams as they pass through air layers of different temperature andpressure. Because light traveling down from a summit passes through many suchlayers, a surveyor could sight a mirage rather than the peak itself. To reducerefraction errors, the Chinese team carried in sea level to within five totwelve miles of Everest’s summit, decreasing the amount of air that lightpassed through on its way to their theodolites. The Chinese also launchedweather balloons near their theodolites to measure atmospheric temperature andpressure changes to better estimate refraction errors. Another hurdle is thepeak’s shape. When surveyors sight the summit, there is a risk they might notall measure the same point. In 1975 the Chinese installed the first surveybeacon on Everest, a red reflector visible through a theodolite for ten miles,as a reference point. One more source of error is the unevenness of sea level.The British assumed that carrying in sea level would extend an imaginary linefrom the shore along Earth’s curve to a point beneath the Himalaya.In reality, sea level varies according to the irregular interior of the planet.The Chinese used a gravity meter to correct for local deviations in sea level.



Q32:  It can be inferred from the passage that refraction would be most likely to cause errors in measurements of a mountain’s elevation under which of the following conditions?

A.    When there are local variations in sea level

B.    When light passes through humid air

C.    When theodolites are used relatively far from the mountain peak.(由旧版答案D改为新版答案C)

D.    When weather balloons indicate low air temperature and pressure.

E.    When sea level has been carried in to within five to twelve miles of the summit.

demonada

V1  【by: arieslee0410】
In 1975 Chinese survey teams remeasured Mount Everest, the highest of the Himalayan mountains. Like the Britishin 1852, they used the age-old technique of “carrying in” sea level: surveyorsmarched inland from the coast for thousands of miles, stopping at increments ofas little as a few feet to measure their elevation, and marking each incrementwith two poles. To measure the difference in elevation between poles, surveyorsused an optical level—a telescope on a level base—placed halfway between thepoles. They sighted each pole, reading off measurements that were then used tocalculate the change in elevation over each increment. In sight of the peaksthe used theodolites telescopes for measuring vertical and horizontal angles—todetermine the elevation of the summit.
TheChinese, however, made efforts to correct for the errors that had plagued theBritish. One source of error is refraction, the bendingof light beams as they pass through air layers of different temperature andpressure. Because light traveling down from a summit passes through many suchlayers, a surveyor could sight a mirage rather than the peak itself. To reducerefraction errors, the Chinese team carried in sea level to within five to twelve miles of Everest’s summit, decreasing the amount of air that lightpassed through on its way to their theodolites. The Chinese also launchedweather balloons near their theodolites to measure atmospheric temperature andpressure changes to better estimate refraction errors. Another hurdle is thepeak’s shape. When surveyors sight the summit, there is a risk they might notall measure the same point. In 1975 the Chinese installed the first surveybeacon on Everest, a red reflector visible through a theodolite for ten miles,as a reference point. One more source of error is the unevenness of sea level.The British assumed that carrying in sea level would extend an imaginary linefrom the shore along Earth’s curve to a point beneath the Himalaya.In reality, sea level varies according to the irregular interior of the planet.The Chinese used a gravity meter to correct for local deviations in sea level.

Q32:  It can be inferred from the passage that refraction would be most likely to cause errors in measurements of a mountain’s elevation under which of the following conditions?
A.    When there are local variations in sea level
B.    When light passes through humid air
C.    When theodolites are used relatively far from the mountain peak.(由旧版答案D改为新版答案C)
D.    When weather balloons indicate low air temperature and pressure.
E.    When sea level has been carried in to within five to twelve miles of the summit.

demonada

大家看一楼。。。俺错了。。。不知咋回事儿就成内样儿了~

Goco

decreasing the amount of air that lightpassed through on its way to their theodolites.    定位句

话说楼主的一楼，是不是哪个阿拉伯国家的jj啊？ 嘿嘿

serenashu

我也记得答案是C

aquatic

我当时做到这里就很疑惑，为啥答案给D，而不是C。

D的低气压和低温并不能表明有多层layer的存在
而C的距离远必定要考虑多层layer造成的误差