Test your language skills on bab.la games site. They have a matching quiz, hangman, and a memorizing/matching game. The fourth choice (German youth word of the year in this screenshot) changes every time you refresh the games page.
You can play the games in many different languages, in three different levels of difficulty. I tried the Japanese matching quiz and found it entertaining, if not always completely accurate.
The mistake: “to slag” is a verb and 「くだらない人」is a noun. I also don’t think that the meaning is the same, but I’m from the US. I’ll have to ask a British-English speaker. I think “to slag” means to criticize. But a「くだらない人」is someone who wastes your time with meaningless drivel.
It was entertaining in part because I found some rather colloquial language mixed with more formal language.
“To hit the road” does mean 「出かける」but the more typical, less colloquial translation would probably be “to go out.”
So, as with any site (or any textbook, I think), don’t take what you find as the only possible answer, or even necessarily a correct answer. If you have questions, talk to your classmates, talk to me, and double-check other sites and books.