"Who is my lawyer?"
Translation:Qui est mon avocat ?
If the following word starts with a vowel, you use 'mon' even for feminine nouns. http://french.about.com/od/grammar/a/adjectives_possessive.htm
The first translation literally means "Who is my lawyer?" while the second means "Who is it that my lawyer is?"
In French, it's much more common than in English to phrase it like that. Take this translation as an example:
What is it? = Qu'est-ce que c'est? (rather than Qu'est il?)
It translates to "What is it that it is?" and the same phrasing is used with verbs
Do you eat chips? = Est-ce que tu aimes les frites? (Is it that you eat chips?)
If you had mistakenly put the wrong possessive, Duo will suggest another noun to fit your possessive. Its algorithm is a bit lacking in that regard.
For example, if you had put "ma avocate," which is not correct, Duo will suggest "ma juriste" instead of the better correction "mon avocate."