ቤተ መጻሕፍቲ ባይዱ
Surface tension is not strong enough to retain drops of water in rocks with large pores but is strong enough to hold on to thin films of water in rocks with small pores.
Slowing down the process of desertification is difficult because of population growth that has spread over large areas of land.
The spread of deserts is considered a very serious problem that can be solved only if large numbers of people in various countries are involved in the effort.
Water in rocks is held in place by large pores and drains away from small size pores through surface tension.
Slowing down the process of desertification is difficult because of population growth that has spread over large areas of land.
The spread of deserts is considered a very serious problem that can be solved only if large numbers of people in various countries are involved in the effort.
Surface tension is not strong enough to retain drops of water in rocks with large pores but is strong enough to hold on to thin films of water in rocks with small pores.
逻辑：因果
主干：Seriousness results from A and B, as well as C or D.
解题要点
Which of the following best expresses the essential information in the highlighted sentence? Incorrect answer choices change the meaning in important ways or leave out essential information.
果：so, so that, therefore, thereby, as a result, hence, thus, consequently, accordingly（用于句首）
因果关系（隐性）
A. 导致（因-果）：cause, reason, lead to, give rise to, result in, make, render , push, fuel, stimulate, spark, spur
Eg. His rude remarks fueled her anger. This accidental killing sparked major riots in the cities. The shock of the discovery rendered him speechless. The girl’s loving care spurred his recovery. Unhygienic conditions give rise to disease.
Desertification is extremely hard to reverse unless the population is reduced in the vast areas affected.
对比转折关系
对比： while, whereas, on the other hand
Desertification is extremely hard to reverse unless the population is reduced in the vast areas affected.
Desertification is a significant problem because it is so hard to reverse and affects large areas of land and great numbers of people.
因果关系（隐性）
B. 由…而来（果-因）：result from, derive from, originate from, stem from, be attributable to
The extreme seriousness of desertification results from the vast areas of land and tremendous numbers of people affected, as well as from the great difficulty of reversing or even slowing the process. (句子转化)
Slowing down the process of desertification is difficult because of population growth that has spread over large areas of land.
（错误，遗漏重要信息。）
The spread of deserts is considered a very serious problem that can be solved only if large numbers of people in various countries are involved in the effort.
转折：but, however, yet, nevertheless, nonetheless, conversely, instead, on the contrary, by contrast
转折（句子转化） ★
If the pores are large, the water in them will exist as drops too heavy for surface tension to hold, and it will drain away; but if the pores are small enough, the water in them will exist as thin films, too light to overcome the force of surface tension holding them in place; then the water will be firmly held.
Water in rocks is held in place by large pores and drains away from small size pores through surface tension.
Small pores and large pores both interact with surface tension to determine whether a rock will hold water as heavy drops or as a thin film.
1. 错误选项的特征： a.改变原意，通常与原句表达意思相反； b.遗漏原句的主要信息。
2. 抓住主要逻辑内容：逻辑关系+主要内容,优先考虑与原句逻辑 关系相同的选项。
3. 题目要求选择的是与原句主要意思相同的句子, 意味着并不是 原句中每一个微小细节都要在正确答案中得到复述。
Desertification is a significant problem because it is so hard to reverse and affects large areas of land and great numbers of people.
托福阅读长难句的逻辑关系
王奇
四大逻辑关系
对比转折关系 ★ 因果关系 ★ 比较关系 否定关系
因果关系（显性）
因：because, for, as, since, in that +句子 because of, on account of +名词或名词短语
eg. She was fortunate in that she had friends to help her. She retired early on account of ill health.
转折（句子转化） ★
If the pores are large, the water in them will exist as drops too heavy for surface tension to hold, and it will drain away; but if the pores are small enough, the water in them will exist as thin films, too light to overcome the force of surface tension holding them in place; then the water will be firmly held.