Why do we need to repeat the verb "to be" in this kind of statements?:
- She is being kind to me.
It is supposed that the second "be" takes a meaning of the verb "behave".
English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. It only takes a minute to sign up.Sign up to join this community
There are two conditions when we repeat the verb "to be".
As we know the Progressive Tense is formed with the help of the helping verb "to be" (past tense or present tense) + Present Participle.
Notice, BBC Learning English suggests to generally avoid using the continuous form of the passive with the future, present perfect, past perfect and future perfect. Such phrases sound clumsy and unnatural.
However, with the future progressive sometimes such usage exists as a prediction of an event (Passive voice):
This Source indicates the opposite:
There is no future progressive for the verb "to be". "Will be being" is expressed simply as "will be".
There's another interesting thing to notice (Source):
Stative adjectives (angry, sad, dead, happy, alive, big, small) cannot normally be used in progressive and imperative constructions.
Dynamic adjectives (rude, kind, polite, honest) can be used in the progressive and imperative constructions.
The present continuous sense in that case is used to emphasize the fact that right at the moment of speaking she treats me nicely, even though at other times she and I might not like each other. For example you and your friend are talking to her in a coffee shop then you two go to the toilet and talk privately together:
You know she hates me right? But she wants to ask for my solution for the exam question, that's why she's being nice to me right now.
Whereas present simple tense (without being) would indicate that generally she behaves in a nice manner to you because she likes you and wants to be friendly.
She is nice to me. We just met for a few days and she always asked me about my day.
Regarding your second question, being can be replaced with behaving in this context and it still keeps the original meaning. But being on its own already explicitly expresses the idea.
The present continuous construction is typically used to describe an action that is happening now (as opposed to usually, or generally).
- She is being kind to me.
The Original Poster asks why we need the verb BE two times in this example. The present continuous construction requires two verbs. The first verb is always the verb BE. The second verb is always an -ing form of a verb. We need both parts to make a present continuous. We cannot indicate that the action is in progress now without this grammar.
The first verb BE here is necessary because it tells us whether the sentence is present tense or past tense:
The second BE is necessary for two reasons. Firstly, we need something to tell us that the phrase kind to me describes the Subject of the sentence. This is one of the jobs that the verb BE does. The second reason we need it is to show that the action is happening now. The second BE does this by (a) occurring after the present tense form of BE and (b) by providing an -ing form of a verb. The -ing form is important because it tells us that the speaker is thinking of an action happening at a specific time, and not communicating that this action generally happens. Compare:
She is being kind to me. (right now - but perhaps she isn't usually kind)
She was kind to me. (probably usually)