Discard the water layer, which contains the aspirin or acetominophen) and evaporate the chloroform layer to dryness under gentle heat. The result is codeine base, a white crystalline powder. Combine 20 mL pyridine and 25 mL conc. HCl in a beaker and heat strongly to 190C to drive off any water.
A simple sentence usually consists of a single finite clause with a finite verb that is independent. More complex sentences may contain multiple clauses. Main clauses (i.e. matrix clauses, independent clauses) are those that can stand alone as a sentence. Subordinate clauses (i.e. embedded clauses, dependent clauses) are those that would be awkward or incomplete alone.
This digital handout categorizes clauses into independent and dependent clauses. This simply means that some clauses can stand by themselves, as separate sentences, and some can't. Another term for dependent clause is subordinate clause: this means that the clause is subordinate to another element (the independent clause) and depends on that other element for its meaning.