Pichugov's exercises often require a "syntactic analysis" (parsing). Don't just copy the answer; look at how the sentence members are identified.
If you are looking for step-by-step solutions for specific exercises, several reputable educational platforms provide them:
Comma usage in complex structures and isolating participial/adverbial phrases. How to Use GDZ Effectively
ГДЗ Русский язык 9 кл. Пичугова практика 2011-160стр.pdf
Phonetics, morphology, and spelling basics.