yes,it is very useful to save a environment.
The environment is useful for animals as it is an animal's natural habitat. It's the same with humans.
it is useful because it can aware all the peoples to now about it and also to protect or environment to such harmful effects
Houseflies are quite useful to the environment as they help in decomposing of substances. They are also used as food by certain animals on earth.
an resource
Because it is freely available and it doesn't damage the environment.
ox, lizard,cow,...
changes both harmful and useful
No, an orchid cannot survive solely with air roots. Orchids need a combination of air roots and traditional roots to absorb water and nutrients from their environment in order to survive.
whle why don't you find a water hyacinth some where and find out
Because the square root of the discriminant is a component of the roots of the equation.
scratch paper