The teacher made great efforts to quiet the students.老师费了很大劲才使学生们安静下来。It requires great efforts to clarify sewage in cities.净化城市的污水需要很大的努力。To achieve this goal, you must have ambition; likewise you need to exert great efforts.要实现这一目标，你必须有雄心壮志，同时还得十分努力。