Introductory it as Subject
This pattern is used to indicate that something is said, thought, or discovered, without indicating who said, thought, or discovered it. The implication is that this is a group of people, people in general, or occasionally an unspecified individual: the context has to determine which of these alternatives applies.This is a productive pattern and occurs occasionally with a large number of verbs concerned with saying, knowing, and thinking, such as add, affirm, compute, decree, deduce, deem, hint, hypothesize, maintain, mention, moot, perceive, postulate, speculate, and stipulate. The verbs listed below are those for which this pattern is frequent.The word that is often omitted, as in the clause It was said he had a good head for business.Verbs with this pattern belong to the following meaning groups:The 'report' groupThe 'think' and 'discover' group
4.1 it be V-ed thatThe passive verb is followed by a that-clause.
|It||was admitted||that the tests were all wrong.|
|It||was agreed||that a new treaty would be signed.|
|It||is estimated||that a hundred people have now died.|