主角: leading role, lead...
合成: to compose, to constitute, compound, synthesis, mixture, synthetic...
怨恨: to resent, to harbor a grudge against, to loathe, resentment, rancor...
后顾之忧: fears of trouble in the rear (idiom); family worries (obstructing freedom of action), worries about the future consequences, often in negative expressions, meaning no worries about anything...
项: back of neck, item, thing, term (in a mathematical formula), sum (of money), classifier for principles, items, clauses, tasks, research projects etc...
