第五章 動詞
動詞是表達句意的精髓，句子的時態、語態等全依靠動詞來體現。
動詞可分為實意動詞（如：go, do, make）、系動詞（如：be, remain, seem）、助動詞和情態動詞（見第七章）
實意動詞又可分為及物動詞，即可接賓語的詞，如：yield, resist, discover；和不及物動詞，即不能直接接賓語的詞，如：go, begin, happen。有很多詞既是及物動詞又是不及物動詞，如：drop, grow, fail
第一節 不定式
不定式是動詞的非謂語形式，它的構成為：to+動詞原形，to可視為不定式的標志詞，兩個動詞常用to連接構成不定式。
不定式可以有多種形式，如：主動式（to drink, to see）、被動式（to be continued, to be understood）、完成式（to have completed, to have been adopted）、進行式（to be leaving）等
不定式在句中常作下列成分：
考點一 不定式作賓語、主語或表語
1. 作賓語：不定式多接在謂語動詞后作賓語
如：He decided to put in a good word for me at the meeting.
I didn’t expect to hear from you so soon.
常用的可接不定式賓語的動詞有：decide, expect, determine, offer, forget, remember, want, prefer, wish, hope, continue, begin, attempt, agree, etc.
例：Human beings are social animals who usually prefer not to live in physical or psychological isolation.
2. 作主語：不定式短語可作主語
如：To see is to believe (百聞不如一見)
To work hard should be your major concern.
注意：由于英文不習慣句子主語過長，不定式主語常被形式主語it所代替(詳見第十七章)
例如上面第二句可以變為： It should be your major concern to work hard.
又如： It is very nice of you to help me.
It is hard for you to carry this heavy box.
3. 作表語：當句子的主語是purpose, aim, duty, goal, hope, plan, suggestion, idea, intention, problem, mistake, reaction等表示“意圖”、“目的”、“功能”等意思的詞時，一般由不定式作表語
如：His only purpose in life is to seek truth.
Our plan was to raise money for the new project.
例題：
(1)
Before the invention of the clock, people had to reliable on the celestial bodies to tell time.
應改為：rely.
解釋：此處to是構成不定式的標志詞, 之后應接動詞原形
(2)
Chinese immigrants began ---- to the United States in large numbers in the middle of the nineteenth century.
(A) come
(B) to come
(C) to have come
(D) have come
答案：B
解釋：空格處需要began的賓語，可以是動名詞或不定式，A, D是動詞原形，可先排除；C是不定式的完成式，不符合begin的用法；只有B正確
(3)
The central purpose of management is for making every action or decision help achieve a carefully chosen goal.
應改為：to make
解釋：主語purpose決定應用不定式作表語，故改為to make
