Indicating a gap actually is to sell the problem that you want to solve in research. Here are three easy-to-use sentence patterns.

學習

國際

This is not only to summarise what they have done and found but also to tell your readers that there is a problem or a knowledge gap in the field.

As a researcher, one of your main tasks is to sell your research ideas if you want your paper to get accepted and published by a journal. 

The three basic samples we mention here are just to help you make the first move. It's not that difficult. It's quite easy to get started. 