動詞時態的一致

對許多英語為第二語言的學生而言，動詞時態的一致性是他們在學習英語過程中所遭遇的困難之一。這一困難在主要主句與附屬子句所表示的時間並不相同的複雜句子中尤其顯而易見。另一項困難是發生在使用亦具有時間感的不定詞、分詞和語氣助動詞時。我們希望下面的列表能有助於寫作者掌握正確的時態一致性。

只要主要子句的動詞不是過去式，也不是過去完成式，那麼附屬子句的動詞可以是任何可以正確表達意思的時態。然而，如果主要子句的動詞是過去式或過去完成式，那麼附屬子句的動詞就必須是過去式或過去完成式。這個規則的例外是，附屬子句是在表達眾所周知的普遍事實和真理：

In the 1950s, English teachers still believed that a background in Latin is essential for an understanding of English.
Columbus somehow knew that the world is round.
Slaveowners widely understood that literacy among oppressed people is a dangerous thing.

獨立子句的時態	附屬子句的目的/附屬子句的時態	例句
簡單現在式	表示同一時間的動作/簡單現在式	I am eager to go to the concert because I love the Wallflowers.
	表示較早的動作/過去式	I know that I made the right choice.
	表示從過去某一時間點持續到現在的一段時間/現在完成式	They believe that they have elected the right candidate.
	表示即將來臨的動作/未來式	The President says that he will veto the bill.
簡單過去式	表示另一完成的動作/過去式	I wanted to go home because I missed my parents.
	表示較早的動作/過去完成式	She knew she had made the right choice.
	敘述普遍的事實和真理/現在式	The Deists believed that the universe is like a giant clock.
現在完成式或過去完成式	無論何種目的/過去式	She has grown 30cm since she turned nine. The crowd had turned nasty before the sheriff returned.
未來式	表示同時發生的動作/現在式	I will be so happy if they fix my car today.
	表示較早的動作/過去式	You will surely pass this exam if you studied hard.
	表示比獨立子句的動作還要早的未來動作/現在完成式	The college will probably close its doors next summer if enrollments have not increased.
未來完成式	無論何種目的/現在式或現在完成式	Most students will have taken sixty credits by the time they graduate. Most students will have taken sixty credits by the time they have graduated.

不定詞與分詞時態的一致

與動詞一樣，不定詞和分詞亦可傳達隨時間改變之動作的觀念。所以，瞭解它們適當的時態一致也很重要。

不定詞
不定詞的時態	不定詞的角色	例句
現在不定詞 (to see)	表示同一時間的動作或比動詞還要晚的動作	Coach Espinoza is eager to try out her new drills. (eagerness 是現在的動作，而 trying out 則是在其後發生)
		She would have liked to see more veterans returning. (現在不定詞 to see 與 would have liked 是同一時間的動作)
完成不定詞 (to have seen)	表示比動詞還要早的動作	The fans would like to have seen some improvement this year. ("Would like" 敘述一種現在情況；而 "to have seen" 則敘述在此時間之前的事情)
		They consider the team to have been coached very well. [完成不定詞 to have been coached 所指的時間比動詞 consider 還要來得早)
分詞
分詞的時態	分詞的角色	例句
現在分詞 (seeing)	表示與動詞同時發生的動作	Working on the fundamentals, the team slowly began to improve. (began 所表達的動作發生在過去，與 working 同時發生)
過去分詞或現在完成分詞	表示比動詞還要早發生的動作	Prepared by last year's experience, the coach knows not to expect too much. (knows 所表達的動作是發生在現在，而 prepared 所表達的時間係在此時間之前)
		Having experimented with several game plans, the coaching staff devised a master strategy. (現在完成分詞 having experimented 所指的時間比過去式動詞 devised 還要來得早)