Formal:
* "The monolingual education system in this country often makes it difficult for immigrant children to succeed."
* "Despite being a monolingual speaker of English, she was able to understand the gist of the conversation using context clues."
* "The research study focused on the cognitive benefits of being raised in a monolingual environment."
Informal:
* "I'm pretty monolingual when it comes to languages, but I'm trying to learn Spanish."
* "My grandma is completely monolingual, she only speaks German."
* "Being monolingual in a globalized world can be a real disadvantage sometimes."
Remember, "monolingual" refers to someone who speaks only one language. You can use it to describe a person, a society, or an environment.