constitute

[piousoul]

1a. Twelve months constitutes a year.
1b. A year is constituted of twelve months.

2. The audience of the concert was largely constituted of young people.

Sentence 1a is taken a dictionary; therefore, it should be correct.
I'm not sure of 1b. and 2; they sound all right to me. To make sure, I would like to have some native friends' feedback.
Thanks.

[Tdol]

It's quite a formal verb, so I don't see any real need to use it in your examples. You could say that a parliament is constituted of..., so the passive form is possible.

[piousoul]

It's quite a formal verb, so I don't see any real need to use it in your examples. You could say that a parliament is constituted of..., so the passive form is possible.

Thanks, Tdol, for your comment. It appears in a test question, and I want native speakers' opinions.