To analyze a complex sentence we use the following method.
1. Find out the principal clause
2. Find out the subordinate clause or clauses
3. Identify the subordinate clause according to its function, as a noun clause, adjective clause or adverb clause.
4. Show how each subordinate clause is related to the principal clause.
5. Analyze separately the principal clause and each subordinate clause as we analyze a simple sentence.
Study the following examples carefully.
When the train stopped, we set out for the next town, where we had planned to stay the night.
Principal clause – We set out for the next town.
Adverb clause of time modifying the verb set out – When the train stopped
Adjective clause qualifying the noun town – where we had planned to stay the night
Analyze the following complex sentence
1. As my son had completed his studies, I decided to send him to town, where he might find a good job.
Principal clause – I decided to send him to town
Adverb clause of cause modifying the verb decided – as my son had completed his studies
Adjective clause qualifying the noun town – where he might find a good job
2. When the siren sounded, all traffic came to a stop.
Principal clause – all traffic came to a stop.
Adverb clause of time modifying the verb came – when the siren sounded