Angel wrote a Notebook entry  http://www.italki.com/entry/599055  in which she asks :

'there is the question : One crucial aspect of Einstein’s training that is overlooked is the years of philosophy he read as a teenager

i cant understand this sentence . what is the "that" mean in this sentence , and two "is " . which is main clause ? this sentence is very coplicated to me .'

'Overlooked' refers to both the 'aspect of Einstein's training', and 'the years of philosophy he read as a teenager'.

I have been trying to analyse this sentence, but am confused myself as to how it could be better written.

Any suggestions ?