My two cents:
Encircle and Surround
Encircle: The island was encircled by a dusty road(from all sides, horizontally).
Surround:The field was surrounded by trees.(from all sides, vertically)
give out :to send out
light, sound, heat etc
The oil lamp gave out a pleasant yellowish light.
The musical triangle gives out a clear, beautiful note when struck.
The stun gun, when applied to the body, gives out a sharp electric shock.
Substances such as ammonia give out heat when they dissolve.(Quoted from Collins Cobuild)
give off :to send out
heat, smells, gas etc as a result of a natural or chemical process
The plant gives off a delicate smell of lemons.
Gas heaters should only be used in well-ventilated rooms as they give off carbon monoxide.
(Above definitions and examples are quoted from
Longman Dict. and its Language Activator)
According to the above examples, sometimes they can be interchangeable, but sometimes they cannot. In our daily usage, we mostly use "give off" for gas, steam while "give out" for light and sound.
(Not a teacher.)
