1. Travelling is a good opportunity to see the world.
2. Nowadays people tarvel not only for pleasure but on business.
3. Travelling by air is the most convenient and comfortable means of travelling.
4. Let's go to the station to see Jack off.
<span>5. We are going on a sea voyage next week.</span>
6 .
6. When
7. Where
8. Though
9. That's why
10. That
долнжо быть was так как это предложение является пассивным залогом в неопределенном прошедшем времени. Или has been если имеет отношение к настоящему времени.