clarify, suggestive, thoughtful

I had lots of doubts about the paragraph. I wanted to make them clear/clarify them with my teacher, so I went up to my teacher. As usual, the teacher gave very simple explanations, which made me to understand the paragraph clearly.

Good explanation is the suggestive of how intelligent the speaker is.

My friend has always thoughtful approach, so he makes hardly any blunders in his life.

I am shouting with so high pitch, but you are pretending as though you are not listened anything. Perhaps you are thoughtful with some other pleasant things, may be about your girlfriend.

Please correct my sentences.