背景介绍

1One of the major topics to be investigated in …is…

被动语句，非常academic

2There is a growing body of literature that recognizes..

单刀直入，切中要点

3Recently, the problem of X has aroused people’s concern

经典开头，像古典乐一样优雅的句式。

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引出研究主题

1A challenging problem which arises in this domain is…

我经常用，哈哈哈

2Research on…has a long tradition

背靠大树好乘凉，a long tradition意味着有很多大佬的文献可以参考~

3A well-known problem with…is that it does not take into account the…

直接指出前人研究的不足之处，为后面展示（吹捧）自己的研究做铺垫。