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The verb 'to be' is, in most cases, what we call a stative verb. These are verbs which refer to states rather than actions, and are hardly ever used in continuous (progressive) verb forms, i.e. present continuous, past continuous, future continuous, etc.

			I am sad at the moment (NOT I am being sad …)
			He was in the kitchen when the phone rang (NOT He was being in the kitchen …)
			I will be in Tenerife this time next week (NOT I will be being in Tenerife …)

However, some verbs that are usually stative can be used in continuous verb forms when they have certain meanings. Be is one of these verbs.

The following sentences are correct because be is used to describe an action and not a state:

			The children are being very naughty (= They are doing naughty things)
			He was being careless (= He was doing something carelessly)

Compare these to the following examples, where be is used to describe a state and not an action:

			I hope you are well. (NOT I hope you are being well).
			He was very happy when his friends arrived. (NOT He was being very happy …)

The other use of the word being is in passive verb forms. We usually make these forms by using tenses of the verb 'to be' followed by a past participle. The following forms are quite common:

Present progressive (am/are/is being + past participle)

The shop is closed because it is being renovated.

Past progressive (was/were being + past participle)

I knew that he was being dishonest.

Passive –ing forms (being + past participle)

They look forward to being invited.

For more information on the use of stative verbs see the following web sites:

http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/stat.htm
http://webster.commnet.edu/grammar/progressive.htm

be + infinitive

Michael Swan mentions the following uses of this structure:

Plans and arrangements: to talk about plans and arrangements (in a formal way), especially when they are official.

The President is to visit Nigeria next month.

Fate: to talk about things which are/were 'hidden in the future'.

I thought we were saying goodbye for ever. But we were to meet again, many years later.

Pre-conditions: in if-clauses, when the main clause expresses something that must happen first if something else is to happen.

We must hurry if we are to get there by lunchtime.

Orders: to give orders.

You can go to the party, but you are not to be back late.

Be + passive infinitive: the passive infinitive (to be + past participle) is often used in notices and instructions.

			This cover is not to be removed.
			The medicine is to be taken three times a day.

(Michael Swan, Practical English Usage, OUP, pp. 87-88)

To see examples of this structure in use, see the Web Concordancer:

http://www.edict.com.hk/concordance/

In the 'search string' field, type "am or is or are or was or were + any common infinitive form, e.g. to have, to do, to get, etc.". Then select a corpus in the 'select corpus' field (We recommend one of The Times corpuses), and click on the 'search for concordances' button.