I know that "sous" is not to be followed by "de": for instance "sous l'escalier" is correct, and "sous de l'escalier" is not.
But what about "en dessous"? Which usage is correct:
- en dessous l'escalier
- en dessous de l'escalier
Also, is it acceptable to use "dessous" alone e.g. "le chien est dessous la table ?" Or "Sort de dessous le lit !"