Consequently, ... ; By contrast, ... ; More importantly, ... ; Furthermore, ... ; Note that since ... ;
It is important to point out that ... ;
It should be noted that ... ;
... has been a fundamental research topic in ... ; ... has demonstrated good performance ;
... can be roughly categorized into two major groups;
... can be classified into three categories;
... can be conducted in a supervised or unsupervised manner;
We have conducted extensive experiments on ... ;
With the development of ... technology, ... ;
As another research line, ... provides an alternative way to ... ;
... can proceed in several ways.