TASK DEFINITION: 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?). 
PROBLEM: It is of crucial importance to estimate the reproductive number ( R0 ) of the novel virus in the early stage of outbreak and make a prediction of daily new cases on the ship.

SOLUTION: background

PROBLEM: This chapter reports the applicability of ionic liquids in the formation of different types of multicomponent reactions.

SOLUTION: purpose

PROBLEM: we here present a comprehensive analysis of putative G-quadruplexes in the genome of all known viruses that can infect humans.

SOLUTION:
purpose