The passive voice is formed by taking the appropriate tense of the verb to be and adding the past participle.

　　Active Voice: The committee reviewed the project.

　　Passive Voice: The project was reviewed by the committee.

　　In most writing, use the active voice. It is more direct and less ambiguous.

　　The passive should only be used if the doer is unknown or unimportant, or if more emphasis is put on the receiver of the action than the doer.

　　Doer unknown: The Jones' car was stolen last week.

　　Doer unimportant: The bells were rung to announce the wedding.

　　Emphasize receiver: Tony was hit by a fastball.

4. 学习多功能where的用法

where在英语中可以引导多种从句，是一个具有多重功能的引导词。where作为连接副词有三个方面的意义：1）在......地方2）有......地方3）到......地方。例如： Where there is a will，there is a way．有志者，事竟成。

He left his key where he could find．他将钥匙放在易找到的地方。

I will go where I want to go．我要去我想去的地方。

现将where引导的从句进行归纳，以使大家准确、全面地掌握其用法。

1) 引导名词性从句

where可以表示"地点"概念，还可以表示"场合"、"形势"、"情况"等概念。如：

Where the meeting will be held is not known yet. (主语从句)

I don't know where I am mistaken. (宾语从句)

You are saying that everyone should be equal, and this is where I disagree. (表语从句)

The question where he has gone puzzles us. (同位语从句)

2) 引导定语从句

where本身在从句中作地点状语，前面可以用表"地点"的名词作先行词，也可以用有地点含义的抽象名词作先行词。如：

I work in a business where almost everyone is waiting for a great chance.

There are cases where the word "mighty" is used as an adverb.

One of the most important rules of joyful living is that judging others takes a great deal of energy and pulls you away from where you want to be.

3) 引导地点状语从句

where引导地点状语从句时，一般修饰句中的动词或动词短语，说明动作发生的地点。其意思相当于at the place where。如：

After the war, a new school building was put up where there had once been a theatre.

You should make it a rule to leave things where you can find them again.

注意：有时，当where引导地点状语从句具有抽象意义表示条件时，一般放在主句之前。

Where there is a will, there is a way.

Where the money is, there is the power.

Where there is no rain, farming is difficult or impossible.

4) where用作关系副词,有时可有引申的用法

能够这样用的常见词有：system, point, situation, state, case, job 等，这样的词后面跟定语从句时，通常具有引申意义，且定语从句引导词用where。

There is system where you can phone and tell us the numbers and you'll get the book.

Gradually we came to the point where we have different opinions.

He is now in a difficult situation where he is likely to lose his job.

They set up a state of their own, where they would be free to keep Negroes as slaves.

I don't care much for pay. I just want to get a job where I can be greatly valued.