HEEELP I'm Brazilian and I can't understand a Calvin comic strip. What does Calvin mean by "she's on to me"

Take the following paragraph and write two separate paragraphs based on it. be sure to properly cite both parenthetically (don’t worry about a works cited) using this: (henderson). 1.) the first paragraph should contain a direct quote from the provided paragraph (the paragraph below). 2.) the second paragraph should contain a paraphrase of the provided information (the paragraph below). trees are in that they provide clean air. trees take in harmful gases from the air such as carbon dioxide, which is what people exhale from their lungs, and turn it into oxygen, which is what we inhale. they complete this process through photosynthesis, which requires carbon dioxide and then releases oxygen. without trees acting as nature's natural filter, the air would quickly become unbreathable to humans.