다음 밑줄 친 otherwise를 가정법 표현으로 고쳐 쓰시오.
Besides broadening students’ knowledge, required courses can also introduce students to possible careers that they otherwise would have known nothing about.
① if there had not been required courses
② if they had not broadened their knowledge
③ if they had not been introduced to possible careers
④ if they had preferred a psychologist to an engineer
⑤ if they had satisfied the social science requirement