Final answer:
The idea that words with multiple forms should be one word or separate words depending on their part of speech is incorrect. Word usage conventions determine the form, and phrases can function as various parts of speech.
Step-by-step explanation:
The statement that phrases that have verb, noun, and adjective forms should appear as separate words when used as verbs and as one word when used as nouns or adjectives is false. It´s important to recognize that whether a word should be one word or two does not solely depend on whether it is used as a verb, noun, or adjective; instead, it depends on specific word conventions and usage in the English language.
Different parts of speech such as nouns, adjectives, verbs, and adverbs play specific roles in sentence structure. A phrase can function as any one of these parts of speech, but its form in a sentence (single or combined word) depends on established usage rather than a simple rule of separation or combination.