So in my grammar book it is these explanation:
We use the with nationality adjectives that end -ese, -ch, -sh, -ss and are used to refer to all the people of that nationality, eg. Chinese, Japanese, Spanish.
The French drink a lot of wine.
The Swiss are famous for their banks.
Are these a right example? It is in the book, so I think it has to be right... I'm very confused... And are theire nationalities without the beginnings I write above?
I think you mean the endings, but that's OK. I know what you mean!
Those are the primary endings (suffixes) used to indicate the people of particular lands, but they are not all inclusive. Here are some others:
American or Americans (-n or -ns)
Iraqi or Iraqis (-i or -is)
http://www.linglish.net/2008/10/22/so-many-nationality-suffixes/
The map here is useful.
http://forums.anandtech.com/showthread.php?t=1331292
The main answer here is interesting.
So I can't say
- The Americans are good in football. -
I have to say
- Americans are good in football. -
?
But these aren't adjectives, aren't they?
You can use "The" or not. It'll be fine. You would probably use "The" only when comparing American teams with other countries' teams.
In both sentences you wrote, "Americans" is serving as a noun (the subject of the sentence). "The" is serving as an article (sort of an adjective), and "good" is an adjective.
That is what confused me so.
In my question I posted what my grammar book says, with the Examples. Are the explanation totaly right?
Yes, the explanation is right.
These terms will be considered nouns if they are serving in a noun's position in the sentence:
The French drink lots of wine.
Americans are good at football.
But these will be considered adjectives if they are used to describe/modify nouns:
French wine is usually excellent.
American football is different from Italian football.
Ok I get this. But French wine is usually excellent wouldn't be right after the explanation. It has to be The French wine is usually excellent. Am I right?
Again, you'd use "The" if you were comparing, but even that is not a hard-and-fast rule:
The French wines are usually better than the Portuguese wines.
or
French wines are usually better than Portuguese wines.
Both sentences are clear in their meaning, whether you use "The" or not. I wish this could be crystal clear for you, but this is a rather "fuzzy" thing in English!
So the rule that stands in my grammar book is not totally right. I can say The Amaricans are good at football even if there isn't one of the suffix that stands in my grammar book.
Right.
Here's another explanation about using articles (the, a, an):
http://grammar.ccc.commnet.edu/grammar/determiners/determiners.htm
In the first paragraph here, you can tell that it's not an easy or consistent "rule" in English. This is what I meant by "fuzzy" above. Sometimes it works; sometimes it doesn't. I wish I could give you an explanation that is crystal clear, but there just isn't one.