Ok, thanks.
I'd better stop by at Walmart... on the net, of course.
10 minutes later...Ok, I've been to Walmart. It looks like the difference between a shirt and a sweater is that a shirt is generally "light", and a sweater is generally "heavier" than a common shirt. Shirts can either be wore under something else or not. Shirts with buttons down the front can also be called "button-down shirts". Shirts that looks very nice and could be wore on more formal occasions can also be called "dress shirts". Shirts that have short sleeves can also be called "polo shirts" or "T-shirts" (I know the difference).
Anyway, all of those can just be called "shirt", and I think "shirt" must be the most general term for something you wear on the upper part of your body. Otherwise, what do you say to the police if you saw someone suspect, but you were not close to him? He was running, and he was wearing a red... hmm shirt? Sweater? I really don't know, I could hardly see it was a person, LOL. So I guess it's "shirt" the general word.
That's what I understand. Is there something wrong?
The only things I don't understand are...
First: how come T-shirts can also have long sleeves? I didn't know this. If so, what would be the difference between a T-shirt with long sleeves and a normal shirt?
Second: Anyone know what a sweatshirt is supposed to be?
Thanks in advance