To make a contraction with a subject pronoun and the verb BE, join the two words and replace the first letter of the conjugated verb BE with an apostrophe.
|I am happy.||I’m happy.|
|You are funny.||You’re funny.|
|She is beautiful.||She’s beautiful.|
|We are hungry.||We’re hungry.|
|They are young.||They’re young.|
The simple present of the verb BE is frequently contracted with the negative adverbe not. A conjugated form of the verb BE is joined to not and the o in not is replaced with an apostrophe.
|The dog is not friendly.||The dog isn’t friendly.|
|They are not home.||They aren’t home.|
It is not possible to contract the simple present of the first person singular form of BE (am) and the negative adverb not.
|I am not happy.|
Note that the verb BE can be contracted with a subject or the negative adverb not. There is no difference in meaning between these phrases.
|uncontracted||with subject||with “not”|
|I am not happy.||I’m not happy.||—|
|You are not late.||You’re not late.||You aren’t late.|
|She is not rich.||She’s not rich.||She isn’t rich.|
|We are not hungry.||We’re not hungry.||We aren’t hungry.|
|They are not young.||They’re not young.||They aren’t young.|
The simple past of the verb BE (was | were) cannot be contracted with a subject.
|I was not there.||xxx|
|You were not home.||xxx|
|She was not sad.||xxx|
|They were not eating.||xxx|
However, the simple past of BE can contract with the negative adverb not.
|I was not there.||I wasn’t there.|
|You were not home.||You weren’t home.|
|She was not sad.||She wasn’t sad.|
|They were not eating.||They weren’t eating.|
In spoken English, contractions are made with any noun followed by the third person form of BE (is). This is informal speech.
|Their dog is big.||Their dog’s big.|
|The building is old.||The building’s old.|
|My idea is better.||My idea’s better.|
Contractions with BE are not possible with a subject when BE is the final word of a sentence (occurring in response to a question).
|Who is going?||I am.|
|Is it noon?||Yes, it is|
|Are they here?||Yes, they are.|