Student or Learner
again I'm in trouble with the concept of a phrase:
Although a very larg proportion studies have been carried out, whenever justified the relationships derived in this and the foloowing vhapters have been kept as general as possible so as to apply to all systems.
In difficult sentences, try to identify the main verb, its subject and, if there is one, its object/complement. That often helps.
Although a very large proportion of studies have been carried out, whenever justified the relationshipsderived in this and the following chapters have been keptas general as possibleso as to apply to all systems.