adaptation is at various levels.. its behavioural and structural..
for eg..in case of human beings if he/ she migrates to another country or land the person will adapt to the language, food,climatic changes in that particular area..this will help for survival,
incase of structural changes during evolution of human race.. man adapted himself for balancing his body on his feet .i.e. bipedal locomotoin..made use of opposable thumb.. however these changes were gradull...which helped him to survive..
AND to make things clear on your side.. sulphur oxide,nitrogen dioxide,carbon monoxide are harmful gases.. they are highly toxic in nature..
minute quantites when inhaled causes death...
there is no questuion that we could not live without these gases

In a way, yes. However, humans are unique as a species in that we can significantly alter our environment and devise technology that allows us to survive in many hostile environments. As a result many humans survive that would, under pure natural selection, cause other species to die. In the most hopeful of worlds, we would adapt and survive. But as evolutionary history points out quite poignantly, those that do not adapt will not survive. A sudden change to which we could not adapt to quickly enough could usher our demise as it has for countless other species.

adaptation depends on what our genes allow us to. But the genetic code can also change in time, and new qualities develop throuhg evolution.
When oxygen first became abundant in our atmosphere it was toxic to most lifeforms. Life has evolved to exist with it, and now we can't leave without it.
So it is true, but within a certain parameters: A bear for example can go into hybernation to adapt to the cold of the winter. It can do that, because it's genes allow for the possibility. If the enviorment was to change very drasticaly it wouldn't be able to adapt to it that fast. That can only happen through evolution and takes a long time.

Living things are always adapting.

We are already able to live in an atmosphere that is 21% elemental oxygen (a poison!) that has been excreted by anarobic bacteria for the last 3 billion years.

The method we use to get it into our lungs, then our bloodstream and then to each cell is a marvel of chemical engineering. Eventually, we and other breathing vertibrates will get used to other atmospheric chemicals, so, YES, it's true.

"adaptation of all living beings including humans is continuous & spontaneous, and human body will adapt itself to the changing environment. So there could be a day when we could not live without harmful gases like Sulphur dioxide, Nitrogen dioxide, carbon monoxide etc."

Do above lines make sense? And could it be true?