Walter offered us a lift when he was leaving the office,but our work not finished,we declined the offer

问题描述:

Walter offered us a lift when he was leaving the office,but our work not finished,we declined the offer
如何改为状语从句?

原句应该是Walter offered us a lift when he was leaving the office,but our work not being finished,we declined the offer
这样对不对:When Walter left the office,he offered us a lift,because we did not finished our work,so we declined the offer