已知数列{a_n}，如果$a_{1,}{a}_2-a_{1,}{a}_3-a_{2,}\cdots ,a_n-a_{n-1,\cdots }$是首项为1公比为2的等比数列，那么a_n=（   ）

    My name is Henry．I'm twelve____old and I have got a small family.My father is a manager____ he works in a hotel.My mother is a doctor．Now we live in Shanghai，a big city____ China.

    My grandparents don't live with____.They are on a farm．On Saturday,I go to see them with my parents．I like to eat noodles with____ ．They are my favourite and they are from the farm．