Why is it not "he wore a hat today"? I thought 了 meant the action already occured.
It's actually for a completed action, not for past ones. 戴 is to out on and the action was complete today, but the hat remained on his head.
Perhaps better English translation then is "He put on a hat today." ?
The better, and accepted, translation is "He wore a hat today". Yours is good too.
What completed action ?!
It's a hat that he's wearing today....
..... Still wearing it
I still don't understand 了 when it's used in the present. I don't know when and how to use it . This sentence seems to me meaningless and meaningful to the same extent, both with and without 了。
You got a good point!!! (Punto)
Could it be also translated to "he brought a hat today?"
"To bring" would be 带 (or 帶 in traditional Chinese), which has the same pronunciation as 戴.
That'd be 帶!
Sorry, phone was bugging out not showing my replies so I practically triple posted haha.
Hey Kal-in, there should be a "delete” under your comments so that you can delete them.
What is the difference between 戴 and 穿?
戴 is mostly used when referring to an accessory : 帽子， 眼镜 (glasses), any jewelry, 手表 (watch), 手套 (gloves)，eventually 围巾(scarf)...
穿 is used with clothes and shoes
To refine this explanation a bit, 戴 refers to objects that are generally set onto the body, whereas 穿 refers to the act of passing one object (your arm, for instance) through another (a shirt sleeve).
What about 他今天戴着帽子？
The sentence seems to be hanging, something needs to be added e.g. 他今天戴着帽子去菜市买东西。
Without 了is it a gross error? Does 他今天戴帽子。mean different?
No, but it is most likely less accurate. It is colloquial, at least to me.
"He has a hat on today". Is that OK to say? I'm asking native English speakers.
Yes, that is OK as an English sentence.
戴 not 帶!
cap or hat?
Just hoping it's not a green one