Verb conjugation of "viaggiare" in Italian

I know it is a little confusing. The problem is if the original word is a conjugated verb: I skipped them until now. I did not write it in my explanations. It actually must be skipped. Thanks for noticing.
The last sentence is the hardest in the entire series. Writing may bore some people, but it is considered the best training in language learning. It is a skill that can lift you from intermediate to advanced level. Do not neglect it.
The course was a bit tough because the teacher always gave lots of homework. We were upset about his behaviour. He was very arrogant towards all the students. It was simply no fun to study there.