A

    Shanghai's Maglev Train(磁悬浮列车) runs from Longyang to Pudong International Airport(国际机场). The whole trip takes about 8 minutes.

    Children at or under 120 cm tall don't need to buy tickets to take the train, but they cannot take the train by themselves. Children above 124 cm must buy a full-price ticket.

    If you buy a round ticket, you can get on the train at Longyang Road Station or Pudong Airport Station, and get off at the other station. The return part of the ticket must be used on the same day.

已知一种碳原子（质子数、中子数均为6）的质量为ag，铝的相对原子质量为b，则一个铝原子的质量为（  ）

— Does your mother often wash clothes for you?

— No. I always wash them ____ (I/myself).

考古人员在北京人遗址中发现，他们用火的遗迹十分集中，灰烬堆得很厚，最厚处有6米，能从这些现象得出的结论是（    ）