Teacher: In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
Teacher: Now, understand the problem? If you are still confused, see the following example:
The Inheritance Cycle is a series of fantasy books written by Christopher Paolini.
Solution: The Inheritance Cycle is a tetralogy of young adult high fantasy novels written by American author Christopher Paolini.
Reason: The output sentence elaborates on the input sentence without changing its general meaning e.g. "tetralogy of young adult high fantasy novels".

Now, solve this instance: Japan 's highly skilled carrier aircrews could not be replaced because the training programs could not produce enough new aircrew .
Student:
Japan 's cadre of highly skilled carrier aircrews with which it began the war were , in effect , irreplaceable because of an institutionalised limitation in its training programs and the absence of a pool of experienced reserves or advanced training programs for new airmen .