也就是說，只要把握好"時間狀語"和"語態(tài)(先行詞與動詞的關系)"，非謂語動詞做定語的考試選項比較容易，出題幾率也比較低。
有人可能會問：
I have a letter to write 和I have a letter to be written兩個句子中的黑體部分都是做"letter"的定語，為什么一個用主動，另一個用被動語態(tài)。一般來說，當動詞(write)的行為者就是句子的主語(I)時，用主動語態(tài)。因此，這兩個句子的內涵是有些區(qū)別的。但由于考試形式的局限性，一般不會考這種區(qū)別的。
4.狀語
非謂語動詞做狀語是這一講的重點，也是考醫(yī).學.全.在.線payment-defi.com試的重點。大家還記得"句子的連接"一講中說過的"逗號不能連接兩個句子"這句話和所舉的例子嗎?
錯：He is ill, he cannot come to the party this evening.(逗號不能連接兩個句子)
對：Because he is ill, he cannot come to the party this evening.(使用連接詞)
對：Being ill, he cannot come to the party this evening.(使用非謂語動詞形式)
如果：His child is ill, he cannot come to the party this evening. 該怎么改呢?
道理是一樣的：
His child being ill, he cannot come to the party this evening.
也就是說，非謂語動詞也要有"行為的主體"，稱為"主格";如果"非謂語動詞的行為的主體"與句子的主語不一致，要保留其行為主體(如上句中的"his child")，這種結構稱為"(分詞)獨立主格結構".
下面每個例子說明一條規(guī)則，注意理解和記憶(重點不要去區(qū)分作什么狀語，也不要刻意去翻譯句子的意思，重點注意形式的轉換和規(guī)律)：
1) When she heard the noise, she went out to see what was happening.
Hearing the noise, she went out to see what was happening.
規(guī)則：當句子的主語(she)與 (非謂語)動詞構成主動語態(tài)時，只要將實義動詞(heard)恢復原形 (hear)，后面加ing即可
2) When (或 If) the substance is heated to over 200℃, it will give off a poisonous gas.
Heated to 200 over 200℃, it (= the substance) will give off a poisonous gas.
規(guī)則：當句子的主語(it = the substance)與 (非謂語) 動詞構成被動語態(tài)時，去掉be動詞，只保留動詞的-ed形式(heated)即可
3) As he did not want to hurt her feelings, he did not tell the truth at the moment.
Not wanting to hurt her feelings, he did not tell the truth at the moment
規(guī)則：非謂語動詞的否定式是在非謂語動詞前面(不是后面)加not構成;其他變化按照例1)或例2)規(guī)定
4) As she has lived in China for over 20 years, she can speak Chinese fluently.
Having lived in China for over 20 years, she can speak Chinese fluently.
As they had not finished the lesso醫(yī)學全在.線payment-defi.comns, the students had to give up going to see the play.
Not having finished the lessons, the students had to give up going to see the play.
規(guī)則：當句子中出現(xiàn)1)"for + 時間"狀語，或2)當一個行為必須在另一個行為結束后才能開始的情況下，應該用"完成式"，否定詞 "not" 要放在"having"的前面，即"Not having…"
提示：當你在考試時分不清是否要用"完成式"時，應傾向于選擇有"完成式"的選項。
5) If weather permits, we'll go out for a picnic tomorrow.
Weather permitting, we'll go out for a picnic tomorrow.
When all necessary data had been collected, they began the experiment.
All necessary data having been collected, they began the experiment.
(注：這個句子也可以寫成：All necessary data collected, they began the experiment.考試時按例4)提示選題)
規(guī)則：當句子的主語與非謂語動詞的主格不一致時，應使用"獨立主格形式"，其他變化按上述各項規(guī)定處理
需要說明的是：
1. 所謂"前置"和"后置"是相對的，這里這樣區(qū)分一是為了便于理解，二是根據(jù)職稱考試中出題的習慣，便于判題;
2. 關于功能，這里只是講了考試中較多出現(xiàn)的形式和結構，對于諸如如何區(qū)分"目的"和"結果"等內容，因與解題關系不大，這里就不作具體說明了。
下面把非謂語動詞中其他幾個重要問題用實例說明一下：
關于"不定式"作后置狀語的舉例(注意黑體字部分的表達形式)：
1) She was so angry as to be unable to speak. (她氣得連話都說不出來了。)
2) I don't know her well enough to ask her for help.(我與她不太熟悉，不便請她幫忙。)
3) She was too angry to say anything.(她氣得什么都說不出來了。)
4) I'm only too glad to help you.
注意與例3)的區(qū)別：only too與happy, pleased, glad 等詞使用時，表示"非常"：我非常愿意幫助你(能幫助你真是太高興了)。
