Detailed Instructions: In this task, you are given two sentences in the English language (Sentence 1 and Sentence 2). Your task is to identify the connecting word between the two sentences.
Q: Sentence 1:On an arbitrary ringed space quasi-coherent sheaves do not necessarily form an abelian category . Sentence 2:On the other hand , the quasi-coherent sheaves on any scheme form an abelian category , and they are extremely useful in that context .
A:
on the other hand