Final answer:
The correct verb to complete the sentence 'Not one of my shirts ______ clean,' is 'is,' as 'one' indicates a singular subject which requires a singular verb.
Step-by-step explanation:
Based on the sentence provided, “Not one of my shirts ______ clean,” the subject is singular despite the mention of multiple shirts because the key phrase is 'not one.' When we refer to 'one,' we are referring to a singular entity, therefore, the correct verb to complete the sentence is “is”. The subject-verb agreement rules dictate that singular subjects take singular verbs. Therefore, the complete sentence should read, “Not one of my shirts is clean.”
When it comes to compound subjects joined by “and,” plural verbs are typically used, such as in the example “Her watch and wallet were stolen from the locker at the train station.” However, when the parts of the subject form a single idea or unit, or when compound subjects are joined by “or” or “nor,” the verb should agree with the word closest to it, exemplified by “Either your mother or your uncles remember your grandmother's gumbo recipe.”