托福閱讀語法解析：非謂語動詞
托福閱讀中不定式和分詞的常見用法有哪些呢?
不定式(to do)的用法
不定式to do可以算是非謂語動詞家族中最神通廣大的一個了，可以說它能夠在句子中充當除了謂語之外的任一成分，它既可以像名詞一樣做句子主干，也可以像形容詞、副詞一樣去做句中修飾成分，接下來我們就結合幾個例句分別來看一下它的用法。
1. 作主干
不定式同動名詞一樣，可以像名詞一樣去使用，在句中充當主干成分，我們通過以下列例句簡單了解一下即可。
To see is to believe.
I like to swim in the afternoon.
2. 作定語
不定式跟在名詞之后時，可以作為定語對前面的名詞進行修飾，用來表示將來目的。
She found a way to solve the problem.
The first generation to experience these changes did not adopt the new attitudes easily. (OG- Artisans and Industrialization)
3. 作狀語
不定式作狀語時位置較靈活，可以出現(xiàn)在句前或句后，最常見用來做目的狀語，如例句1、3，有時也可作其他狀語，如例句2中的不定式狀語就用來表結果了。
To achieve his dream, he works hard everyday.
He woke up to find the door open.
To compare the compositions of a meteorite and the Sun, it is necessary that we use ratios of elements rather than simply the abundances of atoms. (TPO22-3)
分詞(doing、done)的用法
非謂語動詞結構其實是英文寫作中一種重要的擴寫句子的手段，所以在閱讀中也十分常見，尤其是分詞結構。分詞結構能夠作為定語去修飾句中的名詞，也能夠作為狀語出現(xiàn)在所修飾的句子前后，以下是一些具體示例。
1. 分詞作定語
當分詞結構跟在名詞之后，會作為后置定語修飾名詞，只要當做“……的”來理解就好，同時注意現(xiàn)在分詞doing表示主動發(fā)出的動作，過去分詞done則是被動含義。
The man wearing a hat is my neighbor.
I like the book written by that famous novelist.
Abu Hureyra was founded about 9500B.C, a small village settlement of cramped pit dwellings (houses dug partially in the soil) with reed roofs supported by wooden uprights. (TPO20-2)
The semiarid lands bordering the deserts exist in a delicate ecological balance and are limited in their potential to adjust to increased environmental pressures. (TPO2-1)
以上例句中我們討論的是分詞短語作后置定語的用法，實際上分詞也可以單獨使用，在名詞之前作定語，以下就是幾個簡單的例子。
a flying bird
a broken heart
Glaciers may form in permanently cold areas, and these slowly moving masses of ice cut out valleys, carrying with them huge quantities of eroded rock debris. (OG- Geology and Landscape)
2. 分詞作狀語
當分詞結構出現(xiàn)在某個句子主干之前或之后，則作為該句子的狀語。理解的時候注意兩點，第一，分詞結構的邏輯主語和被修飾句子的主語一致;第二，現(xiàn)在分詞doing表示主動動作，過去分詞done則為被動含義。分詞狀語可以被看作是狀語從句的簡化形式，所以我們可以將分詞狀語等同于狀語從句來理解。此外，分詞狀語位于句末常常作為結果或伴隨狀語，所以我們也可以直接將它當做并列句來理解，比如下方的例句二和例句四。
Accepting others’ criticisms, people can make progress.
He dropped the cup, breaking it into pieces.
Praised by the teacher, the boy is very happy.
Growing tightly packed together and collectively weaving a dense canopy of branches, a stand of red alder trees can totally dominate a site to the exclusion of almost everything else. (老托98.05)
Carbon dioxide in the air reacts with the rainwater, forming a weak acid (carbonic acid) that may chemically attack the rock. (OG- Geology and Landscape)
