Brett,
Of course she knows Mandarin, Everyone under the age of i think, 45 knows it because that is the Official language of China!! That is the only Language that is used in all Schools, Collages, and Universities, as well as ALL government offices and about 9/10th's of all TV channels and Radio stations.... That's not to say that those in the South may use Cantonese, as there everyday language, but they will sure know Mandarin
...Now go to Hong Kong, Macao, or Taiwan, and you'd probably be on a loser with your Mandarin, But Mainland China, .....No Problem!!!
David.......