Of course it can.
no, greece is not land locked
no
Sudan
Yes.
No, its a land locked country
Laos
No, Switzerland is a land-locked country.
Moldova
No, it is an island!
Afghanistan is a land locked country.
Switzerland is the only landlocked country in the question's list.
Chad, Mongolia just to cite landlocked countries. Israel, Tunisia if the definition of "ocean" is stricto sensu (they are bordered by the Mediterranean Sea, not an ocean). Only some island countries (Australia, etc..) are "surrounded" completely by water.