2009 Revised Edition: The revised edition was typed in Microsoft Word with Unicode font to guarantee a searchable full-text format. Previous Zuyin (注音) phonetic markers were updated to Hanyu Pinyin (漢語拼音) with tone markers. Some missing Chinese characters in the first edition, due to limitation of character type font on the Chinese typewriter, were added and typos were corrected. Endnotes were changed to footnotes for easy reading. Lessons with mixed traditional and simplified characters were changed to use either traditional or simplified characters throughout.