比比皆是: can be found everywhere...
变迁: changes, vicissitudes...
记载: to write down, to record, written account...
发现: to find, to discover...
义务: duty, obligation, volunteer (work etc)...
去: to go, to go to (a place), (of a time etc) last, just passed, to send, to remove, to get rid of, to reduce, to be apart from in space or time, to die (euphemism), to play (a part), (when used eithe...
卷子: test paper, examination paper...
学会: to learn, to master, institute, learned society, (scholarly) association...
焦急: anxiety, anxious...
撤离: to withdraw from, to evacuate...
