Four weeks study in Beijing? it is called the intensive program or summer camp. It is a package including tuition, boarding and meals. Moreover, the school even can arrange the airport pick up and transportation services. I wonder!!! your sister is 17, she is a minor, how can she get the visa to China? and what kind of visa that China has issued, tourist or student Visa? Write to the school, ask them for more information about the Intensive or Summer program package deal. additionally, you will need to have your parents to appoint you as the legal guardian for your sister. When you arrive China, the first thing to do is to register your stay in China at France consulate. So, your country will know where you are, provide safe protection and other assistance as needed. I registered with The US consultate, when I was in France.

I have to say that there is no such thing as 'Beijing Foreign Languages University', as Cindy said above. But I believe she meant Beijing Foreign Studies University. Beijing Language and Culture University is the best, I think. They call it 'the little UN', because it has students from all parts of the world. It specialises in teaching Chinese.