Consider
I entered the class and said "Hello" to everybody. At this time/ At the moment / At the same time/ suddenly / meanwhile a student asked out load "Sorry! are you going to teach a new course today"
Maybe it wasn't a good example. But I want to know what English use when they want to say at the same time (immediately after or during) another thing, something else happened? I mean when they narrate something maybe as a narrating device.
The literal translation of what I mean is "at this time" or "at this moment", but I'm not sure about their similar usage in English. When these phrases are used by the way?