Honestly, these lessons on sentence structures almost did me in, as do all grammar lessons--I'm far more comfortable teaching about the art of writing, and not the mechanics. The best I can do, I'm afraid, is to give you this link, which takes a fairly easy approach to complex and compound-complex sentences.
https://www.englishgrammar101.com/modul ... -sentences
I can probably answer specific questions, but I'm not sure that I'm qualified to give guidance on this from ground zero.
Sorry.
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