In order to activate again the last command used previously to the current one, we will use Shift Key + letter or number from the previous command. As it’s shown in pictures bellow tasks and commands have letter or numbers.
For example we are drawing a rectangule and we would like to draw a smartline or another command we were using belonging to this group “Q”,then we press Shift + Q and MicroStation will turn back to smartline command and the same it would be if we used previously "Copy" command which belongs to task group 3 pressing Shift + 3