Q.In the sentence: "When a young man's heart turns to thoughts of love, it must be spring." Is the first clause in the this sentence adverbial, adjectival or nounal?
I think it is adverbial relating to time. The word "When" can be used to introduce all three type clauses. Is there some rule that will help me?
A. You're right, the first clause is adverbial. It tells when it must be spring. There's no rule so far as I know to help distinguish between different types of clauses. It is the sense of what it does in the sentence. If it describes an action or state of being, it is an adverbial clause. If it describes a noun, it is an adjective clause. If if performs a function in the sentence, such as subject or object, it is a noun clause.