Using Sentences to Qualify Nouns
You can also use sentences to qualify nouns.
Ex: きのうかった本(the book that I bought yesterday.)
Ex: かれがくれた本(the book my boyfriend gave me.)
Qualifier sentences in these examples tell us what kind of book we are talking about, just like adjectives. The verbs used in such qualifier sentences are in thier short forms, either in the present, and either in the affirmative or negative. When the subject of the verb appears inside a qualifier sentence, it is accompanied by the particle が, and not は.