This is a correctly written piece of dialogue. It is both grammatical and conveys meaning which leads us to believe that it is correct.
Emily and Tamra are both proper nouns. Careful is an adverb. Stuff is a noun. Is is a verb. With is a preposition. And always is an adverb.
Scientist believe farmers will grow plants with black leaves. The black leave will be able to change sunlight into energy. Stain believes that these black leaves will help reduce poverty in rural parts of the world. He also believes that termites will eat rusty metal and trees will produce liquid fuel.
I hope this helps, sorry it’s a little long.
