Bolivar had received aid from Haiti and hadin return to in the areas he .
Bolivar had received aid from Haiti and had promised in return to abolish slavery in the areas he liberated(a).
主语(Bolivar)+并列谓宾(had received aid 和had promised to abolish slavery)。
“in the areas……”这部分是介词短语作地点状语，其中a部分是省略引导词(that/which)的定语从句，修饰the areas。
Bolivar(主)had promised(谓)to abolish slavery in the areas he(主) liberated(谓)