Solution

(a) Air helps movement of $$water$$ $$boats$$.
(b) Air speeds up drying up of $$agricultural$$ $$products$$ like grains, pulses, fruits etc. Air helps in pollination of flowers and dispersal of seeds.
(c) $$Windmills$$ work where there is sufficient movement of air.
(d) Air filled tyres of $$cars$$ and $$Scooters$$ move smoothly on road as there is less friction.