Same thing could be said about English. :) Begin, start, commence, initiate, instigate, launch... I suppose all languages have synonyms for 'most every word.
I don't know enough to know what the "best word" for finished would be, it probably depends on context at least sometimes. But terminar, completar, finalizar, and concluir are some ways to say finish.
I would really report this but the only option offered is that the SPANISH sentence is unnatural. As mentioned below, 'we can begin the studies' is very poor English except in very very peculiar circumstances, and 'We can begin our studies' does need to be added to the possible answers.