Final answer:
A nonrestrictive element is a phrase or clause that provides additional information. It is set off with dashes. In this case, the nonrestrictive element can be added to the sentence to provide extra information.
Step-by-step explanation:
A nonrestrictive element is a phrase or clause that provides additional information that is not essential to the meaning of the sentence. It is set off with dashes to indicate that it can be removed from the sentence without changing the main message.
In this case, we can rewrite the sentence using a nonrestrictive element as follows: 'My mother doesn't have enough time to volunteer at school - a fact that often frustrates her.' The nonrestrictive element 'a fact that often frustrates her' adds extra information but is not necessary for understanding the main point of the sentence.
To rewrite the sentence 'My mother doesn't have enough time to volunteer at school' using a nonrestrictive element with dashes, you would include additional information about the mother that isn't critical to the meaning of the sentence but provides more context.
Here is how you can rewrite it: 'My mother, who is always busy with work and home responsibilities - doesn't have enough time to volunteer at school.' In this rewritten sentence, the dash is used to add emphasis to the nonrestrictive element, which is the additional information about why the mother is too busy to volunteer.