In this task, you are given a sentence from the research paper and your task is to classify the given sentence into the following categories: Background (Why is this problem important? What relevant works have been created before? What is still missing in the previous works? What are the high-level research questions? How might this help other research or researchers?), Purpose (What specific things do the researchers want to do? What specific knowledge do the researchers want to gain? What specific hypothesis do the researchers want to test?), Method (How did the researchers do the work or find what they sought? What are the procedures and steps of the research?), or Finding (What did the researchers find out? Did the proposed methods work? Did the thing behave as the researchers expected?). 
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Question: Viruses with mutations in nsp5 and nsp16 produced small DMVs but also replicated normally.

Answer: method


Question: In addition , an open-platform system is described that utilizes standardized reagents and methods and allows the user to develop in-house protocols.

Answer: purpose


Question: spring source water , and water from the public water supply system.

Answer:
purpose