This cleared up exactly what I was struggling with on the drills. I'm really enjoying the foundation portion of the study guide.

This is what helped me. The kernels [subject, predicate and object] should be a grammatically correct sentence when pulled out from the complex sentence; Ex: Mary Simms declared.

Alfred Wegener developed a concept

The formation is triggered.

Except Here:

[A] study concluded. Even though A is a modifier, I still pulled it from the sentence. I didn't have to change the definite article to make the sentence correct.