if you have dual responsibilities in a company like administrative officer and executive secretary, how can you focus on your objectives?

It's tricky...you have to look after both areas, there's no two ways about it. You have to make both parties happy and time management is always going to be a challenge. Getting in there early before everyone else does help in terms of planning and preparing for the busy day ahead, and keeping away non urgent things for later also helps. I'd say to maintain composure and a friendly attitude at all times, and provide updates to people in case things are getting delayed.