Which sentence includes a dependent clause
Today is her 16 birthday
The package was heavy.
She smiled as she opened the package.
It was a fancy hat
She smiled as she opened the package.
Looks like someone received a present worth smiling about! And in this sentence, "as she opened the package" is the dependent clause. It's relying on the main clause "She smiled" to make sense. Together, they're like two peas in a pod, or, in this case, two parts of a sentence.