Verified answer

Ответ:

1. modern transportation system is well developed
2. which was carried
3. the first transport was traced
4. modern railroad was introduced
5. the first airplane flight was made
6. the first human spaceflight was launched

Объяснение:

В тексте 6 комбинаций с Passive Voice, подчеркнула именно сказуемое в ответе