【How to Write】Indicate a gap/research niche

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.