——has given birth to ----that people could barely imagined-----
However, I believe that although online course is an advantageous alternative to---it can never be asubsitute for the latter.
-----have been expressing their concer that ----
on the one hand ----on the other hand---
Nonetheless ,according to my experience---
First of all ----second----last but not least
What is most important is that ---
at the same time ,we should be clearly aware that---
with the constantly increasing popularity of-----has emerged into people's vision
