17. My father is a police officer. Hes _________________(FREQUENTLY) away from home. 18. Traveling by train is the best option for long-distance travel. They are clean, _______________ (COMFORT) and punctual. 19. I like traveling by motorbike because its a great way to get around Hồ Chí Minh city __________________(QUICK). 20. In the UK, there are several __________________(DIFFER) kinds of public transportation.