roofs were totally riffled off / the World Robot Cup competition / lost the championship...
1.
The strong hurricane destroyed a lot of houses, some of whose roofs were totally riffled off.
→Is this senten correct? What does "riffled off" mean here? Is it correct?

2.
Dozens of teams, only a few of which can enter the final stage and compete for the Championship, joined the World Robot Cup competition.
→Is this senten correct? Why is the word Championship capatalized? Is it correct? What's "the World Robot Cup competition"? Is it correct?

3.
The students in my class lost the championship of the World Robot Cup, some of whose parents were not very happy about the news.
→Is this senten correct? What's "the World Robot Cup"? Is it correct?

Thanks!

Question

roofs were totally riffled off /  the World Robot Cup competition / lost the championship...
1.
The strong hurricane destroyed a lot of houses, some of whose roofs were totally riffled off.
→Is this senten correct? What does "riffled off" mean here? Is it correct?

2.
Dozens of teams, only a few of which can enter the final stage and compete for the Championship, joined the World Robot Cup competition.
→Is this senten correct? Why is the word Championship capatalized? Is it correct? What's "the World Robot Cup competition"? Is it correct?

3.
The students in my class lost the championship of the World Robot Cup, some of whose parents were not very happy about the news.
→Is this senten correct? What's "the World Robot Cup"? Is it correct?

Thanks!

Answer

1. You probably mean "ripped off".
2. Yes, it's correct, although I would prefer "entered" to "joined" as the verb. Capitalization of "Championship" is OK if it refers to a previous mention of a proper noun, for example, "World Robot Championship". However, if that name is actually the "WR Cup" we also see mentioned, then  "championship" should be lower case, referring to the common noun.
3. Incorrect. "Whose" here would refer to the WRC, which is presumably parentless.

Answer

Maybe they changed the name?

Answer

Thanks for your advice. In fact, I've googled "the World Robot Cup competition" before, but it seems that there is no World Robot Cup competition. I only found this - "RoboCup is an annual international robotics competition proposed[1] and founded in 1997." (Wiki) Here is the link: https://en.wikipedia.org/wiki/RoboCup
So, that's why I ask here. I want to know if "the World Robot Cup competition" is correct or not.

Answer

It's easy to find out what the World Robot Cup competition and the World Robot Cup are.  I think you should research that on your own. You'll learn a lot more that way.

Answer

Riffled is a word but here the correct word is ripped.