A subordinate clause is patterned like a sentence, with both a subject and a verb, but it begins with a word that marks it as subordinate. The following words commonly introduce subordinate clauses.
after | before | so that | until | while |
although | even though | than | when | who |
as | how | that | where | whom |
as if | if | though | whether | whose |
because | since | unless | which | why |
Subordinate clauses function within sentences as adjectives, as adverbs, or as nouns. They cannot stand alone. (See 48e.)
Most fragmented clauses beg to be pulled into a sentence nearby.
Because introduces a subordinate clause, so it cannot stand alone. (For punctuation of subordinate clauses appearing at the end of a sentence, see 33f.)
Although introduces a subordinate clause, so it cannot stand alone. (For punctuation of subordinate clauses at the beginning of a sentence, see 32b.)
If a fragmented clause cannot be attached to a nearby sentence or if you feel that attaching it would be awkward, try turning the clause into a sentence. The simplest way to do this is to delete the opening word or words that mark it as subordinate.