Firstly partnership accounts are not in the syllabus for Paper FA (was F3) and have not been in the syllabus for many, many years.
Secondly, whatever the nature of the business (sole trader, partnership, or limited company) they can use any method they want to calculate depreciation as I explain in my free lectures. In the exam it is either reducing balance or straight line, but you are told which.
I suggest that you watch my free lectures. They are a complete free course for Paper FA (F3) and cover everything needed to be able to pass the exam well.