While writing my history essays, I've run into some issues in the past with being marked off for not writing in the past tense. I'm a bit confused about the complications of some of my sentences and trying to put them into the past tense.
Is this sentence fully in the past tense?
This suggested that one must approach the interpretation of a historical figure with consideration to the prevailing atmospheres, states of affairs, and conditions present with respect to that period in time, and only then, by virtue of this approach, would one be able to accurately evaluate a historical event or figure.
I'm specifically wondering if my use of "suggested" in the beginning sets the whole sentence to be in the past tense, but when I say "would one be able to accurately evaluate a historical event" I don't know if it has to be changed. If it is wrong, would this be correct phrasing? - "would one have been able to have accurately evaluated"
In other words, do all verbs have to be in the past tense to meet this requirement? I am writing about what a historian said in an essay if that helps. Also, as a secondary question, could my list of considerations be phrased as "prevailing atmosphere, state of affairs, and conditions" or do they all have to be plural since I want conditions to be plural?