To what event it’s lincoln referring when he says, “ on the occasion corresponding to this four years ago..”

what are the phrases to choose from?

explanation:

ward, and charles cooley, felt that social conflict was a process that should be in exploring social processes and social problems. conflict as a functional social process." 

depends on your school

when i was in high school i took ap biology my senior year and it was the hardest one for me because my teacher finished the material within the first month of school and then went on to doing advanced college level it was horrible. but at a nearby school ap biology was one of the easier aps. also, it depends on what you are interested i like math a lot so ap calculus was easier for me than most but i hate history so ap us government was harder for me than most.

the universe is complete credible source of our oxygen