其實長難句在考試中最直接的運用就是考察插入句子題和解釋句子題。對于這樣的題目，我們在不能讀懂句子的情況下，能夠把握的就是句子的內(nèi)在關(guān)系，即邏輯。邏輯在解釋句子題中的運用尤為重要，以前有學生反映，在考試中其實句子根本就不能讀懂，而利用邏輯就能迅速排除選項，從而找到正確的答案。所以說，邏輯是我們托福閱讀中的隱形解題幫手，考生們一定要尤為關(guān)注。

下面是托福閱讀中經(jīng)常出現(xiàn)的四大邏輯關(guān)系，把握了它們就等于掌握了托福閱讀解題技巧的一個重要部分。

1． 因果關(guān)系

因：because, because of, for, as, since, in that, on account of, with
果：so, so that, therefore, thereby, as a result, hence, thus, consequently, accordingly

因果關(guān)系除了傳統(tǒng)意義上的顯性因果表達詞外，隱性的因果同樣是不可忽略的一個重要部分。

隱性因果：

A 導(dǎo)致（因-果）：cause, reason, lead to, give rise to, result in, render, make, let, ask, support, push, stimulate, spark, spur, fuel, produce, be responsible for

如The increased pressures of expanding populations have led to the removal of woody plants so that many cities and towns are surrounded by large areas completely lacking in trees and shrubs.
在這段話中，有l(wèi)ead to, 表示了導(dǎo)致的意思，即結(jié)果; 而so that 更進一步表示了后面的結(jié)果，所以可以充分判定這段話有因果關(guān)系的邏輯。

B 由…而來（果-因）：result from, derive from, originate from, initiate from, stem from, be responsive to, be attributable to?

如 “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.”
在這段話中，根據(jù)result from可以推斷出有因果關(guān)系，那如果是解釋句子題時，選項中有因果關(guān)系就可以優(yōu)先考慮。

C 反映，體現(xiàn)(果-因): reflect, present, demonstrate, suggest, imply, show
This result demonstrates that…

D 考慮到: given, considering, in view of, thanks to, according to
He succeeded thanks to (in view of) his effort.

E 依賴于: rely on, depend on, resort to,
He resorted to books when he had problems.
?
F 條件關(guān)系：when, once, as soon as, as long as
As soon as he got the money, he would leave the country at once.

G? 分詞短語，不定式做狀語
Failing in the final exam, she cried.

2． 對比轉(zhuǎn)折關(guān)系

A 對比：while, whereas, on the other hand

在解釋句子題，插入句子題中，一旦出現(xiàn)對比關(guān)系，學生在掌握的基礎(chǔ)上就能非?？焖俚呐卸ň溟g和句內(nèi)的關(guān)系。While, whereas 前后連接的是平行結(jié)構(gòu)，on the other hand前必定有on one hand, 可以用來把握句間關(guān)系。

B 轉(zhuǎn)折：but, although, despite, in spite of, nevertheless, however

轉(zhuǎn)折是托福閱讀的一個經(jīng)典考點之一，掌握這些轉(zhuǎn)折詞對考試非常有幫助。

3． 比較關(guān)系

A 同級比較 as…as

B 比較級：more…than, -er than, less…than

C 變化：change, alter, vary, modify, revise, increase, decrease, enhance, diminish, develop, progress, advance, improve, retreat, degenerate, continue, remain

D 差異：different, distinguish, separate, same, similar, comparable, compare…to

E 超越：surpass, exceed, excel, over

F 最高級
1)本身有最高級含義：maximum, minimum, peak, outstanding, top
2) 本身程度比較深：amazing, surprising, astonishing, prohibitively high
3) 否定+比較=最高級
No one is more outstanding than him.
從這句話中可以看出，否定加比較表示的是一種最高級關(guān)系。

4． 否定關(guān)系

顯性否定：no, not, never, nor, none neither

隱形否定：fail to, refuse, remove, miss, reject, absence of, lack of

否定前綴：a-, ab-, dis-,? il-, im-, in-, non- , un- ?
否定前綴是詞匯題中經(jīng)常出的一個考點，把握否定前綴可以幫助考生把握一些生詞，依靠否定前綴對選項進行一個排除。

雙重否定;not fail to, not illegal, not uncommon, not unavailable
雙重否定是英文中經(jīng)常運用的表達方式，由于在平時中文對話中用的很少，隨意對雙重否定的把握就顯得特別的重要。