前面加介词in，例如：
1、In your free time， explore all that this incredible city has to offer.您可以在闲暇时间探索这座美妙城市的各种风情。
2、External recovery refers to actions that take place outside of work — e.g. in the free time between the work days， and during weekends， holidays or vacations.外在恢复指的是工作之外发生的行为——例如，工作日之间的空闲时间以及周末、公共假期或其他假期。
3、Once I had a boy who worked experimentally with Tinkertoys in his free time.曾经我遇到了一个男孩，他在业余时间用万能工匠做实验。
