1. Which type of accounts require adjustment
2. how does depreciation expense affect the adjusting process

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(Although quite personally, I don't think Q1 has a real definitive answer. That could be something specific your book/instructor wants.)

Adjustments affect one Balance Sheet Account and one Income Statemnet Account.

Oh, that kind of "what type of account." I was off thinking about specific accounts, of which there could be a million... :-)