多亏了现代科技 thanks to modern technology 过去 before/used to be 过去在办公室工作的人可以在家办公 Those employees who used to sit in the office can work at home today 周末加班 work overtime on weekends 补课 the classes are not arranged at school, but in some special organizations or training schools 必须的 undoubtedly/for sure/required