1.Many people consider it necessary to adopt such test.
2.Some regard the test as being unnecessary.
I don’t really understand why there are no “is” after 1.“it” and 2.“as”?
Can anyone help me?Thank you.
What you’re seeing in your first sentence is called a “small clause”. In syntax, this term is used to describe a type of clause that has a noun phrase (NP) as a subject, and then any other type of phrase, such as a verb phrase (VP), a prepositional phrase (PP), an adjective phrase (AP), etc., as a complement. It has no position for an auxiliary verb, or for the verb to be (am, is, are, etc.), so there is no verb tense, and often no verb.
Examples:
Full sentence: John is president of the club.
As a small clause: They elected John president of the club.
They elected [color=blue]NP[John[color=blue]] NP[president of the club[color=blue]]
Full sentence: The test is unnecessary.
As a small clause: They consider the test unnecessary.
They elected [color=blue]NP[the test[color=blue]] AP[unnecessary[color=blue]]
It is necessary to adopt such a test.
Many people consider [color=blue]NP[it[color=blue]] AP[necessary to adopt such a test[color=blue]].
In your sentence number 2, the word being is a gerund taking the place of the word is after the preposition as. You have the idiom to regard [noun] as [noun phrase or adjective phrase]:
Some people regard him as [color=blue]NP[the best person for the job[color=blue]].
Some regard the test as [color=blue]NP[being unnecessary[color=blue]].
The noun in this sentence is the gerund “being”.
Notice that you can say the same thing using just the adjective “unnecessary”:
Some regard the test as [color=blue]AP[unnecessary[color=blue]].
I got it now.Thank you very much. 