有現在進行式既問題想問問?

Mary 係正在向逐個逐個學生道歉。

Mary is apologizing to every student (of the class) now.

"for a event"是你原文沒有的，亦不知你所指的event是出了甚麼問題才要道歉，所以這部份刪去。不過假如你想講出道歉的原因，就不能只說FOR THE EVENT，而是要講出她在這event中的錯處是甚麼。並且是在主句...now之後才附加這理由。例如：

Mary is apologizing to every student now for being late in the event.

Mary is apologizing to every student now for making a error in the performance.

Mary is apologizing to every student now for overspending on food.

Some verbs don't have the aggressive form, i think this sentence is a little bit weird. Maybe you can use the simple form " Mary apologizes to the student for a event now.