In an office该题为简答填空题。根据"At first，he worked in an office，but soon he found that it was boring"．可知此处应填in an office。

When Tim left school, he did not really know what he wanted to do. At first, he worked in an office, but soon he found that it was boring. There was also trouble with his second job in a car factory. He then decided to work out of doors, and got a job as a gardener in a park. Now he works much harder than he did in the office or in the factory, because his work is more varied. He works hardest in autumn and winter, keeping the park tidy and preparing for spring and summer. In summer he can relax and he can feel proud that he has helped to make the park so beautiful. Many people visit the park and he is always pleased when he hears them say how lovely it looks.