The sentence

The use of ‘by’ + agent (= ‘doer’) after a passive
1. We use by only when we need to say who or what is responsible for a event:
The window was broken last night. (We don’t know or want to say who or what did it.)
The window was broken by a slate that fell off the roof. (We wish to give information.)
2. We often use by + agent with the passive of verbs like build, compare, damage, design,
destroy, discover, invent, make and write to identify who or what is/was responsible:
Who designed St Paul’s? – It was designed by Christopher Wren.
The passive with verbs of ‘saying’ and ‘believing’: ‘It is said (that) …’
We need to be sure of our facts when we say: e.g. He was a spy in World War II.
If we are not sure of our facts, we can express caution by saying:
It is said (that) he was a spy in World War II./ He was said to be a spy in World War II.
We can express caution in three ways, with:
1. It (+ passive + that-clause) with e.g. agree, believe, consider, decide, hope, know, say:
It is said (that) there is plenty of oil off our own coast.
2. There (+ passive + to be) with e.g. allege, believe, fear, know, report, say, suppose, think:
There is said to be plenty of oil our own coast.
3. Subject (not it) (+ passive + to-infinitive) with e.g. allege, believe, consider, know, say:
Jane is said to know all there is to know about chimpanzees.
C. form and use of the causative
Form of the causative: ‘have something done’
1. Note the difference between these two sentences:
I had built a house. (past perfect tense = ‘I did it myself’
I had a house built. (the causative = ‘I arranged for it to be done’
2. We form the causative with have + noun or pronoun object + past participle.
We use the causative in different tense and with modals:
I am having a house built. I had a house built. I have had a house built.
I will have a house built. I must have a house built. I can’t have a house built. etc.
The causative compared with the active and passive
1. We use the active to describe jobs we do ourselves or when we know who’s doing a job:
I’m serving the car. Jack is servicing the car.
2. We use the passive to say that a job is being done for us, but we don’t know or don’t want
to say who is doing it:
The car is being serviced. (We’re focusing on the car)
3. We use the causative to stress the fact that we are ‘causing’ someone to do a job for us:
I’m having the car serviced. I have had my car serviced. I’m going to have my hair
cut. Not *I’m going to cut my hair* which means ‘I’m going to cut it myself’.
We often use the causative with verbs that have to do with services: e.g. build, clean,
decorate, develop (a film), mend, photocopy, press, print, repair, service.
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