Sites like GDZ.ru often list supplemental materials for the 7th-grade Russian language curriculum, though they primarily focus on standard textbooks and workbooks by authors like Bystrova or Ladyzhenskaya.
Prepositions, conjunctions, and particles (specifically the distinction between ne and ni ). lingvisticheskii trenazher bogdanova 7 klass otvety
Formation, suffixes, and punctuation in participial phrases. Sites like GDZ
Spelling of "not" ( ne ) with gerunds and isolating gerund phrases. Adverbs: Comparative degrees and spelling of suffixes. lingvisticheskii trenazher bogdanova 7 klass otvety