def add_columns(pdf):
    """
    Add several columns to specified Pandas DataFrame.
    """
    pdf['c04470'] = pdf['c04470'].where((pdf['c00100'] > 0.0) & (pdf[
        'c04470'] > pdf['_standard']), 0.0)
    pdf['num_returns_ItemDed'] = pdf['s006'].where((pdf['c00100'] > 0.0) &
        (pdf['c04470'] > 0.0), 0.0)
    pdf['num_returns_StandardDed'] = pdf['s006'].where((pdf['c00100'] > 0.0
        ) & (pdf['_standard'] > 0.0), 0.0)
    pdf['num_returns_AMT'] = pdf['s006'].where(pdf['c09600'] > 0.0, 0.0)
    return pdf
