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: He was replaced by General Henry G. Winkelman who decided that in the north the Grebbe Line would be where the battle was to be fought , partly because it would be easier to counterattack .
Student:
He was replaced by General Henry G. Winkelman who decided that in the north the Grebbe Line would be the main defence line where the decisive battle was to be waged , partly because it would there be easier to break out with a counteroffensive if the conditions were favourable .