A more comprehensive definition of "sea level," one useful to
[#permalink]
04 Jun 2021, 17:12
para1
to introduce the topic the article intend to discuss about-sea level, in that it be influenced by lots of factors and it seems relatively consistent throughout the history, for now, we can, by the use of more advanced scientific method, to hone our prediction to its measurement
para2
to break down the mechanism behind the landscape of Earth, for gravity and centrifugal field exert its influence on equator and poles that determine the sea level on specific area and shape the Earth’s landscape we see today
1.According to the passage, which is true of the physical forces governing sea level?
A. Gravity, along with rotation, is responsible for Earth's slightly ellipsoid shape.
see sentence in para2: The oceans are governed primarily by Earth's gravity, which is strongest at the poles because of Earth's slightly ellipsoid shape, the result of billions of years of rotation.
so simplify the logic:
Earth billions of years of rotation--> Earth's slightly ellipsoid shape--> Earth's gravity--> govern the ocean, strongest at the poles
(A)would be correct if it change its statement to “rotation is responsible for Earth's slightly ellipsoid shape, which constitute the gravity”
B. Centrifugal deterioration will eventually give rise to an enormous supercontinent.
see sentence in para2: Over time, the bulge of ocean at the equator, no longer held in place by the centrifugal forces, would flatten out. ….. of the globe, leading to the emergence of a supercontinent around the planet's equator.
--> so according to the passage, it’s the “totally disappearance” of the centrifugal, not “deterioration” give rise to the supercontinent, notice the delicacy of the use of words, also the question ask about what kind of “force” control the sea level, statement in this choice—which talks about “centrifugal deterioration”, seems irrelevant to the force we want to find
C. The centrifugal force is the dominant influence on the shape of Earth's oceans.
this choice is incorrect, as can be seen in very obvious way
see sentence:
The oceans are governed primarily by Earth's gravity, which is strongest at the poles because of Earth's slightly ellipsoid shape, the result of billions of years of rotation.
-->so its Earth’s slightly ellipsoid shape cause the gravity to perform to its greatest force at the poles
What keeps the oceans from pooling at the poles, drawn there by the greater gravitational forces, is the centrifugal force generated by Earth's rotation. …. Over time, the bulge of ocean at the equator, no longer held in place by the centrifugal forces, would flatten out.
--> it is centrifugal force that keeps the oceans from pooling at the poles and cause the bulge of ocean, whether this force affect the shape of Earth's oceans we can’t trace from the passage
D. The equatorial bulge is primarily a result of gravitational pooling at Earth's poles.
see sentence: What keeps the oceans from pooling at the poles, drawn there by the greater gravitational forces, is the centrifugal force generated by Earth's rotation. This force is strong enough to cause a bulge of ocean about eight kilometers high around Earth's equator.*
-->thus, the equatorial bulge is primarily a result of “Earth’s rotation”, which give rise to the gravitational centrifuge that made the disappearance of Earth poles’ pooling, so (D) would be correct if it rectifies as “The equatorial bulge is primarily a result of THE DISAPPEARANCE of gravitational pooling at Earth's poles
E. Gravitational forces have more influence on the oceans than does centrifugal force.
I don’t think this one be the perfect answer choice, though this one talks about “force” that respond to what the question ask, now see sentences in para2:
The oceans are governed primarily by Earth's gravity, which is strongest at the poles because of Earth's slightly ellipsoid shape, the result of billions of years of rotation. What keeps the oceans from pooling at the poles, drawn there by the greater gravitational forces, is the centrifugal force generated by Earth's rotation. Using sophisticated computer models, today's cartographers can postulate how the intersection of sea and land would change should the Earth ever cease to rotate on its axis. Over time, the bulge of ocean at the equator, no longer held in place by the centrifugal forces, would flatten out.
….sea level in ocean is determined by Earth’s gravity force, which among them have the centrifugal force, greater in its magnitude, that keeps the oceans from pooling at the poles
….there’re no very clear comparison between gravitational and centrifugal force to the influence on the ocean, if we really want to explain we could only explain in that the range that gravity force influence is much larger than centrifugal force, which only influence the south and north pole
2.The author makes all of the following statements about historic sea levels EXCEPT
First, consider the history of sea level: the position at which sea and land meet, averaged over tidal stages and coastlines, has been remarkably stable over time. Current sea level measures, though having risen very slightly over the last century, are approximately the same as they were 35,000 years ago. Thus, the referent for terrestrial altitudes and oceanic depths has been largely consistent for millennia, though cartographers' ability to make accurate measurements has, of course, improved with advances in technology.
A. Variations in them have been noted in the last 35,000 years.
see sentence:
Current sea level measures, though having risen very slightly over the last century, are approximately the same as they were 35,000 years ago
….so we could see that variation in sea level have indeed been noted/measured throughout this 35,000 years
B. Their consistency has allowed cartographers to improve their measurements.
….correct
see sentence:
Thus, the referent for terrestrial altitudes and oceanic depths has been largely consistent for millennia, though cartographers' ability to make accurate measurements has, of course, improved with advances in technology.
consistency and the improvement of measurement are two parallel things in the original sentence, there’re no cause and effect, in that it must be one allow the another to happen, exist
C. While mutable, they have, broadly speaking, maintained stability for millennia.
this sentence correspond to choice (C):
the position at which sea and land meet, averaged over tidal stages and coastlines, has been remarkably stable over time.
D. They are measured at many times and places to obtain a useful average.
see sentence:
consider the history of sea level: the position at which sea and land meet, averaged over tidal stages and coastlines(at many places), has been remarkably stable “over time”(at many time).
E. Measurements of depth and elevation are made relative to their height.
….history of sea level…been remarkably stable over time. “Thus” the referent for terrestrial altitudes and oceanic depths has been largely consistent for millennia….. though cartographers' ability to make accurate measurements has……
-->so “sea level”, or say, “sea height” are closely connected to the measurement of altitudes and depth
3.The passage is chiefly concerned with
A. imparting an understanding of the effect of Earth's physical forces on sea life
B. arguing that the long-term stability of sea level assists in cartographic accuracy
C. attempting to compose an explanation of one of Earth's topographical variables
….correct
Drawn by the pull of the two poles, Earth's main bodies of water would eventually become circumpolar, gathered in two massive pools around the top and bottom, so to speak, of the globe, leading to the emergence of a supercontinent around the planet's equator.
para2 points out the mechanism of gravitational force, with its show up and disappearance, it is in the last part of the article explain the formation of Earth's topographical map--supercontinent
D. integrating hard data and thought experimentation to better visualize sea level
E. positing a worst-case scenario to educate readers about Earth's fragile balance
close
