If you want help with this or any other JAA-type "Ground School" question, I suggest that you post it on the "Ground School" section of the <a href="http://www.oxfordaviation.net/forum" target="_blank">@SK OXFORD FORUMS</a>,where it will be answered by an experienced instructor.
You don't have to be an Oxford student to use the forum.
Click on the above link or go to <a href="http://www.oxfordaviation.net/forum." target="_blank">http://www.oxfordaviation.net/forum.</a>
All the best,
Paul