Answer:
2. conocía
3. suspendíamos
4. conozco
Step-by-step explanation:
change depending on the last letters in the word: ar/ir/er/ etc
for example using yo:
comer -> yo comía
caminar: > yo caminaba
substitir: - yo substituía
in the future you can check the word on spanishdict, and itll show you all the different forms for imperfect verbs including subjunctive & indicative !