Once you have mastered the basic elements of English grammar it will be relatively easy to learn other aspects of English grammar as they flow on from each other.
An ‘adverb clause’ is a subordinate clause that modifies a verb, an adjective, or another adverb. It tells when, where, how, to what extent or under what conditions.
Example: ‘Before winter began,’ I planted bulbs. [The adverb clause tells when and modifies the verb planted.] Bulbs usually do well ‘if you use fertilizer’. [The adverb clause tells under what conditions and modifies the adverb well.]
Example: The flowers are beautiful ‘because the winter was mild’. [The adverb clause tells why and modifies the adjective beautiful.] In the colloquial speech of most cultures including English words tend to be omitted when they are easily inserted or understood.
‘Elliptical adverb clauses’ have words left out of them. You can easily supply the omitted words because they are understood or implied. Example: The hyacinths are more fragrant ‘than the tulips’ [are fragrant]. ‘While [I am] gardening,’ I always take time to enjoy the flowers.