Question

There can be several sources in indoor e.g. in of air pollution. Tobacco smoke are one of the (a) ________ ________ most important air pollutants on closed places. (b) ________ ________ ‘Passive smoking’ or environmental tobacco smoke pollution can leads to all the harmful effects of (c) ________ ________ tobacco smoking, seen on the smokers and (d) ________ ________ in their non-smoking companions.

Answer 1

Answer:

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