Richard, 1. Situation is said to be critical. 2. These types of Nouns are said to be in Possessive Case In these two sentences a special phrasal verb construction "to be said to" is used. It is similar to the verbs "to be supposed to" and "to be alleged to". The verb "to be said to" indicates a reported fact or an alleged fact that the writer/speaker may not be certain about. It can be followed by "be" or another verb examples, These raincoats are said to be waterproof. A genie is said to live forever. The man is said to have been arrested by the police. 3. These trees are not to be found elsewhere. In this sentence the infinitive "to be" is used to express the future. These trees are not found elsewhere...........You can't find these trees elsewhere. These trees are not to be found elsewhere......You will not find these trees elsewhere.(even if you look) "To" can be used with other verbs to express the future. example, The president is to leave the capitol tonight........The president will leave the capitol tonight. Or in newspaper headline style: .... President To Leave Capitol Tonight

I think you want us to explain the use of 'be to' (Not 'to be'): This is the structure: be to + infinitive Examples: It is to leave... He is to go... It is said to be critical... They are to be delivered ... We use this structure for an official arrangement and in news reports: The cinema is to close in November, it was announced. The Prime Minister is to visit Budapest. The two leaders are to meet for talks on a number of issues. It can also express an order by a person in authority, e.g. a teacher or parent: The headmaster says you are to come at once. You're not to stay up late. No one is to leave this building. This trolley is not to be removed from the station.