解释下列词语的古今意思.
博士:古义______;今义 ______.
治:古义______;今义______.
孤:古义______;今义______.
但:古义______;今义______.
见:古义______;今义______.
往事:古义______;今义______.
过:古义______;今义______.
就:古义______;今义______.