Indicating a gap actually is to sell the problem that you want to solve in research. So, how can we highlight a problem or a knowledge gap in our papers? Here are three easy-to-use sentence patterns.
However,/While/Although......
e.g., To date, however, few studies have been done on the effects of educational big data on teaching-and-learning management.
...... is/are still lacking/limited.
e.g., The research evidence to support AI adoption in tracking students' learning behaviour is still limited.Little is known about...
e.g., Little is known about the development frameworks and evaluation methods of hybrid learning spaces.