All of the example sentences that we have considered up to this point have been in what is known as the active voice. However, this ignores a major type of sentence construction that is sometimes used in speaking, but is more frequently met in the written language - this construction is called the passive.
Look at the contrast between 'active' and 'passive':
- George Bush started the war.
- The people grow rice in Asia.
- I heated the chemicals to 200 Celsius.
- The war was started by George Bush.
- Rice is grown in Asia.
- The chemicals were heated to 200 Celsius.
The first sentence uses an active verb because we are saying what somebody (or in other cases, something) DID: we want to say what Bush did. In the second sentence, we are interested in what HAPPENED, so a passive verb is used. In the first sentence, Bush is the object; in the second, he is the subject.
In the second active sentence, the focus is on who grows the rice; in the second passive sentence it is on the rice. Who grows it is unimportant.
In the third passive sentence, the person who heated the chemicals is not important and, following the convention of reporting of a scientific experiment, is not stated.
We make the passive with the verb be in the tense that we require, followed by the past participle. Sometimes, in place of the verb be, we use get often with very little change in meaning, but get is usually preferred when the action is unexpected, unwelcome, or happens in the face of adversity. Get also tends to be informal than be. Here are some short examples of passive sentences.
- Rice is grown in China.
- My computer is being repaired at the moment.
- The thief was arrested.
- All mistakes have been rectified.
- Harry might have been involved in an accident.
- Applications must be received before the end of the year.
The main verb usually ends in -ed but, as we saw earlier, some verbs have irregular past participles as in the first sentence. In active sentences the order of the elements of a sentence usually follows the pattern subject - verb - object, like this:
- That man stole my wallet.
- I painted this picture.
In these examples the subject or 'doer' of the verb is that man and I respectively, while my wallet and this picture are the objects. The main purpose of the passive is to change the focus of attention of the sentence, so it is often used when the more important information is:
- what happened to the subject - I've been robbed!
- who or what carried out the action - Guernica was painted by Picasso.
- how the action was carried out - the concerto was played beautifully.
- when the doer is unknown - this house was built in 1845.
If we want to include the identity of the doer, then it has to move to the end of the sentence preceded by the word by. So, in the second sentence above we obviously need to know the identity of the artist that painted Guernica otherwise the sentence makes no sense. (The active form of this sentence is Picasso painted Guernica.)
If you look back to the first set of numbered sentences above you will notice that the doer is missing in every case and yet the sentences are still logical and complete. The doers are either unknown, unnecessary or can be guessed from the context, so, for example, in sentence number 3 we can automatically add by the police.