We may form Complex Sentences by using one of the two patterns below:
When I looked into the mirror, I saw a pretty woman.
I saw a pretty woman when I looked into the mirror.
Until Johan attended SERI ABIM, he had no focus in life.
Johan had no focus in life until he attended SERI ABIM.
Joining words (subordinating conjunctions): As, As if, Because, Since, Although, Even though, When, While, Until, Unless, Where, etc.
Pattern 1 Joining word Subject + Predicate, Subject + Predicate.
Pattern 2 Subject + Predicate joining word Subject + Predicate.
It is important to know that sentences containing adjective clauses are also complex:
The woman whom my mom talked to is her cousin.
The cat that Johan found was dead.
The town where I grew up is in Johor.
Subject + Adjective Clause + Predicate