一、不定式和動名詞作主語與表語的比較表示具體的、一次性的或?qū)淼膭幼饔貌欢ㄊ?；表示一般的、泛指的或習慣性的行為用動名詞。
如：◎ ________ is a good form of exercise for both young and old. (全國卷)
A. The walk???????????????????????
B. Walking
C. To walk?????????????????????????
D. Walk
【分析】答案選B。a good form暗示泛指一般性行為，用動名詞作主語。說明：①有時這種區(qū)別并不很嚴格。但要注意：主語和表語要用同一種形式；平行結構中要用同一種形式。

如：◎ —What do you think made Mary so upset? — ________ her new bike. (上海卷)
A. As she lost?????????????????????
B. Lost
C. Losing???????????????????????????
D. Because of losing
【分析】答案選C。去掉問句中的插入語do you think，便知要回答的是主語what。選項中只有動名詞Losing可作主語，全句應為：Losing her new bike made Mary so upset. 此處的動名詞短語表示的是具體的一回事。

◎ The purpose of new technologies is to make life easier, ________ it more difficult. (全國卷)
A. not make????????????????????????
B. not to make
C. not making?????????????????????
D. do not make
【分析】答案選B。前面用的是不定式作表語，與之并列的也應用不定式。

◎ Fishing is his favorite hobby, and ________. (上海卷)
A. he’d like to collect coins as well??????????
B. he feels like collecting coins, too
C. to collect coins is also his hobby?????????
D. collecting coins also gives him great pleasure
【分析】答案選D。and連接兩個并列句，前一分句用-ing形式作主語，與之并列的后一分句也應用-ing形式作主語。 ②通常只用動名詞用主語的4種情況：在疑問句中；在It is no good / use…, It is useless…, There is no…等句型中；在某些動詞的被動式前；在No smoking!之類的布告語中。如：1. Is doing morning exercises good for your health? 做早操對身體有益處嗎？2. It’s useless arguing with them. 和他們討論是沒用的。3. Walking on the grass is forbidden. 禁止在這草地上行走。 ③通常只用不定式作主語的4種情況：在It is necessary / important / …(for sb. ) to do sth. 句型中；It is kind / foolish / …(of sb. ) to do sth. 句型中；在It takes sb. time to do sth. 型句中；主語被否定時。如：1. It is necessary for us to master a foreign language. 我們有必要掌握一門外語。2. It is very kind of you to help us. 你幫助我們真是太好了。3. It took me two hours to finish the work. 我完成那項工作用了兩小時。4. Not to have hope is the poorest of all conditions. 絕望是最糟糕的事。
　　
二、不定式、動名詞、分詞作表語的比較不定式和動名詞作表語相當于名詞作表語，表示主語的內(nèi)容，主語和表語可以對調(diào)；分詞作表語相當于形容詞作表語，主語和表語不可對調(diào)；現(xiàn)在分詞作表語表示主語所具有的性質(zhì)特征，過去分詞作表語表示主語所處的狀態(tài)。如不定式和動名詞作表語相當于名詞作表語，表示主語的內(nèi)容，主語和表語可以對調(diào)；分詞1. My job is teaching / to teach English. (作表語的teaching / to teach English是my job的具體內(nèi)容，可說成Teaching / To teach English is my job. )3. The movie is exciting. (exciting是主語the movie是性質(zhì)特征。)4. They are excited at the news. (excited表示they現(xiàn)在所處的狀態(tài)上海卷

【分析】答案選C。表示“就坐”的seat是及物動詞，若后面沒有sb. 或oneself作其賓語，就一定是seated，所以選C；此處的過去分詞seated表示狀態(tài)，remain=continue to be依然，保持。注：在seem, appear, prove(結果是、后來表明), remain(尚須)等連系動詞后，可用不定式作表語，但不用-ing形式作表語。

如：Having a trip abroad is certainly good for the old couple, but it remains　 ________ whether they will enjoy it. (全國卷)
A. to see????????????????????????????????????
B. to be seen
C. seeing????????????????????????????????????
D. seen
【分析】答案選B。remain作“尚須“解，后面通常接不定式；it(形式主語，指whether they will enjoy it)與see是被動關系，所以用不定式的被動式。