Is the "chiếc" necessary? I put "Tôi mặc một áo mới" and it was marked incorrect, although I seem to remember classifiers being explained as optional in their usage.
Chiếc is necessary in this sentence because it emphasizes a particular shirt that the speaker is talking about. Note that the use of classifier is not optional but varies depending on the context.
Sorry, but how the heck should I know the speaker wants to emphasize that particular shirt and not just report a banal information of wearing something new? I suppose I used to feel enthusiastic about (in a similar situation) as I was a child...
If one were emphasising a particular new shirt, the English would be "I wear THIS new shirt".
the solution tells me to use chiec, but there is no chiec to put in my answer... WTF?!
I was marked wrong even though 'chiếc' was not even available to use...
Chiec vs cai