oxford_guide_to_english_grammar

13 THE PASSIVE PAGE 138
109 The passive with verbs of reporting
There are two special patterns with verbs of reporting.
Active: They say that elephants have good memories.
Passive: It is said that elephants have good memories-
Elephants are said to have good memories.
There is an example of each pattern in this paragraph.
STONEHENGE
It is now thought that Stonehenge - the great stone circle - dates from about
1900 BC. Until recently the circle was popularly believed to be a Druid temple
and a place of human sacrifice, but this is not in fact so. The stones were put up
long before the Druids came to Britain.
1 It + passive verb + finite clause
It is thought that Stonehenge dates from about 1900 BC.
This pattern is often used in news reports where there is no need to mention the
source of the information.
It was reported that the army was crossing the frontier.
It has been shown that the theory is correct.
It is proposed that prices should increase next year.
In Pattern 1 we can use these verbs:
admit declare hope propose show
agree discover intend prove state
allege establish know recommend suggest
announce estimate mention regret suppose
assume expect notice report think
believe explain object request understand
claim fear observe reveal
consider feel presume say
decide find promise see
2 Subject + passive verb + to-infinitive
Compare these patterns.
Pattern 1: It is thought that Stonehenge dates from about 1900 BC.
Pattern 2: Stonehenge is thought to date from about 1900 BC.
In Pattern 2 we can use these verbs:
allege declare find presume see
assume discover intend prove show
believe estimate know report suppose
claim expect mean reveal think
consider feel observe say understand
The infinitive can also be perfect or continuous, or it can be passive.
The army was reported to be crossing the frontier.
The prisoner is known to have behaved violently in the past.
Stonehenge is thought to have been built over a period of 500 years.