This text investigates the complex functional and syntactic roles of modal verbs within the English language. The authors, Richard Wakely and Tom McArthur, utilize a structured linguistic framework to categorize how modal verbs express necessity, possibility, and obligation. By analyzing common usage patterns and grammatical constraints, the book provides a systematic approach for learners and educators to master these auxiliary verbs.

The subject matter points to a technical, pedagogical resource intended for students and instructors of English as a second language. Its focus on structural clarity suggests a traditional, rule-based approach to linguistic instruction that remains a staple in academic reference collections.