What does it mean when a supreme court case is called a landmark case?

Which sentence best explains how steam power changed agriculture in england between 1810 and 1850? a. farmers started using steam-powered machines to spray chemical fertilizers and pesticides. b. livestock farmers began using steam-powered machines to milk cattle and shear sheep. c. steam-powered railways transport and sell agricultural produce far from where it was grown. d. steamships to transport large numbers of people from the united states to english farms.

What happened in the tinker v des monies? and why is it important what happened in the hazlewood v. kuhlmeier? why is it important?

One drawback of voluntary trade is that it a.requires two groups to use a common language b.can make one group dependent upon another for necessary goods c.doesn't occur unless there is a shortage of goods for at least one group d.forces groups to rely on themselves to produce all the goods they need