Proper Nouns: Principal Billsley
Improper nouns: letter,company, roller coaster, school’s backyard, opportunity
I HOPE THIS HELPED
In the text book i think that is right
A complex sentence has a main clause and a dependant or subordinate clause right after, joining the two is subordinate conjunction.
Example:
You should always contribute to society since it will improve the lives of many people.
(You should always contribute to society) main clause.
(Since) subordinate clause
(Since it will improve the lives of many people)
dependent clause
Hope it helped. :D