Match the following academic words with their definitions or synonyms. ____ 1 shroud a easy to obtain or use ____ 2 accessible b suppose ____ 3 explicitly c requirement for sth.to happen or exist ____ 4 presume d hide information or keep it secret and mysterious ____ 5 affirmative e supporter ____ 6 protagonist f the word "yes” or a sign that you agree with sth. ____ 7 prerequisite g clearly and exactly