A subordinate or dependent clause is one that is not a sentence on its own, but modifies the larger context in which it appears: “the man who came here yesterday was very angry”. Many subordinate clauses begin with relative pronouns, as in the previous example: “who”.
Like many languages, Quenya has adverbs whose primary function is to modify verbs, in much the same way that the primary function of adjectives is to modify nouns. In English, there is the suffix “-ly” which can be used to turn adjectives into adverbs, as in “the quick man ran” vs. “the man ran quickly”.
In Tolkien’s later writing, Quenya did not have a direct equivalent of English’s comparative “-er” suffix. In linguistic notes from 1966-67, Tolkien said that “A is brighter than B” is expressed using the preposition lá “beyond”: A (ná) calima lá B (PE17/90), where the copula ná- “to be” is optional as usual.