Why is it useful for historians to base certain studies on the analysis of historical themes?

If one thinks illegal immigrants should become american citizens, should they become american citizens automatically or should there be a waiting period?

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.

Before the civil war, the constitution protected slavery -true -false