解題思路實例分析：
例1：[結果]These plants are termed opportunists because [原因]they rely on their seeds’ falling into settings where competing plants have been removed by natural processes, such as along an eroding riverbank, on landslips, or where a tree falls and creates a gap in the forest canopy.
A. Because [原因]their seeds grow in places where competing plants are no longer present, [結果]dandelions are classified as opportunists.
B. [結果]Dandelions are called opportunists because [原因]they contribute to the natural processes of erosion and the creation of gaps in the forest canopy.
C. The term opportunists apply to plants whose seeds fall in places where they can compete with the seeds of other plants.
D. The term opportunists apply to plants whose falling seeds are removed by natural processes.
妳發現原句中有個because，就知道這句話是在解釋，必定有因有果。我們先去找因和果。結果是這些植物被稱為機會主義者，原因是它們依賴種子掉進壹個環境，後面說這個環境裏競爭性的植物已經被移除了，即沒有競爭性的環境。對句子稍做整理後變成，因為它們依賴自己的種子掉進壹個沒有競爭性的環境，所以這些植物被稱為機會主義者。
有同學會問，後面的such as要怎麽處理。壹般我們有個原則，在句子當中如果是補充的信息，那很重要;如果是重復的信息，應該是不重要的。所以看such as只要明白壹點，它到底給前面的什麽內容舉例。看例子的內容，會發現說的都是地方，說明是給setting舉例，那麽就可以把它放在壹邊。
於是，我們明白作者原句的意圖是在解釋有因果的關系，那麽四個選項中正確的答案必定在邏輯關系和講話的意圖上和原句是壹樣的。發現A、B、C、D中只有A和B是有因果的，再進壹步看具體的內容，可知A的原因和結果都與原句壹致，為正確選項。
例2 [轉折前]Estimates indicate that the aquifer contains enough water to fill Lake Huron, but unfortunately, [轉折後]under the semiarid climatic conditions that presently exist in the region, rates of addition to the aquifer are minimal, amounting to about half a centimeter a year.
A. Despite the current impressive size of the Ogallala aquifer, the region’s climate keeps the rates of water addition very small.
B. Although the aquifer has been adding water at the rate of only half a centimeter a year, it will eventually accumulate enough water of fill Lake Huron.
C. Because of the region’s present climatic conditions, water is being added each year to the aquifer.
D. Even when the region experiences unfortunate climatic conditions, the rates of addition of water continue to increase.
這個題目原句中有壹個but unfortunately，說明這句話前後有壹個轉折，那麽它最核心的意義是作者前後表示的不同。
看轉折前：aquifer地下蓄水層還有足夠的水來填滿休倫湖。雖然我們不知道休倫湖有多大，但妳明白作者的意圖是說水很多。
轉折後：在這個半幹旱的條件下，補充率很小。Amounting to後面給出補充率的數字，是重復內容不重要。
所以明確轉折前說水量大，轉折後說補充率小。然後我們看四個選項，正確答案壹定在邏輯關系的表達上是跟But屬於同壹個範疇。A有despite，表示轉折、讓步;B有although，讓步;C有個因果，原文沒有存在因果;D有even表示讓步。所以在四個選項中我們會優先考慮A、B、D這三個選項。
仔細看A選項，despite後的內容表示水量大，和原句轉折前相同;而逗號後的內容表示補充率小，和原句轉折後相同。所以A是正確選項。