"He is wearing a hat today."
In my personal and humble opinion, the Chinese sentence does not seem to be the corresponding translation. 了 is a very flexible particle and can be used in many instances. If you look at this link:
you will see that "modal 了" can be used when a situation has changed or when informing someone about a new situation. The problem with this Chinese sentence is that "modal 了" always goes at the end of the sentence. On the other hand, "aspectual 了" always follows the verb.
So maybe to actually convey the novelty they should placed the "modal 了" at the end of the sentence like so: 他今天戴帽子了。 This sentence conveys more meaning than the actual translation. Beside "wearing a hat today", the guy in the sentence probably does not usually wear hats (maybe because he has a majestic lion like mane that would be such a shame to hide) and this could be considered as a "changed or new situation". Therefore I think that the issue is with the Chinese sentence.
I rest my case!
P.S. If I am incorrect please let me know and show me some sources if possible :) Thanks!!
The nuance that you mentioned in given sentence isn't fully translated in English, but it is still acceptable. On the other hand, putting 了 at the end has a past tense implication to it, so that it can be translated as "He wore a hat today". Please note that there is, in most cases and in this case as well, no error in the Chinese sentence.
The fact that "戴" means "put on" as well as "wear", which have different aspects in English, makes this a little confusing, but the grammar explanations Andrea links to do seem to support her interpretation. However, I appreciate your native ear.
I tried the neutral "他今天戴帽子", but it wasn't accepted.
According to my girlfriend: 他今天戴帽子 is a neutral statement meaning "He is wearing a hat today." 他今天戴了帽子 puts a slight emphasis on the fact that he usually does not wear a hat, and could maybe best be translated with "Today he is wearing a hat." 他今天戴帽子了 expresses strongly that a change has happened. This could be translated in English with "Today, he is wearing a hat." or "Finally, he is wearing a hat today". 他今天戴了帽子 cannot mean "He wore a hat today" because the particle 了 does not signify past tense when in combination with a present time indicator like 今天. One could for example say 他今天早上戴了帽子: "He wore a hat this morning."
Many people are suggesting that the English sentence is implying he doesn't usually wear a hat. In fact in my opinion it is a neutral sentence with no such nuance. I believe people are trying to imagine a scenario where the sentence would be used. But if you don't, and just look at the plain sentence, there is no difference in emphasis between "today he is wearing a hat." and "he is wearing a hat today". The meaning and lack of any emphasis is the same.
Imho 今天他戴帽子 is sufficient to translate this sentence (duo won't currently accept this).
"Today" is significant in that it delineates the specific time frame, or it suggests a difference from some other day (even if it's just to suggest that, in contrast to today, we don't know about any other day — or why say "today" at all?), but you're right that it doesn't say anything about his general habits, and "today he is wearing a hat" and "he is wearing a hat today" aren't distinguishable from one another in terms of nuance.
That said, it's still worth thinking about the different possible versions of the Chinese, what they could mean, and how they should be thought of. Some suggestions:
- 他今天戴帽子。 He's wearing a hat today. (This is a simple statement of fact.)
- 他今天戴帽子了。 He is wearing a hat today (which may be a change from the usual case). / He wore a hat today.
- 他今天戴了帽子。 He (has) put on a hat today.
I welcome further comments.