Fox are wily.

The plural form of {fox} is to add -es because {fox} is ended with -x.

Foxes are wily.

Fox are also vile.

The same problem mentioned above.

Foxes are also vile.

Fox like to creep in grass.

The same problem mentioned above.

Foxes like to creep in the grass.

Fox like to eat pork.

The same problem mentioned above.

Foxes like to eat pork.