Answer:
To correct the sentence grammatically, you can make the following changes:
The dentist told her she should brush twice every day, floss every day, and sometimes use mouthwash.
Step-by-step explanation:
1. Remove the "to" before "sometimes use mouthwash" to maintain parallelism in the sentence.
2. By removing the "to," the verb "use" becomes an infinitive without the "to" particle.
Revised sentence:
The dentist told her she should brush twice every day, floss every day, and sometimes use mouthwash.
Step-by-step explanation: