第一部分 阅读理解（共两节，满分40分）
第一节（共15题；每小题2分，满分30分）
阅读下列短文，从每题所给的四个选项（A、B、C和D）中，选出最佳选项。
A
Tyler was born infected with HIV and his mother was also infected.From the very beginning of his life,he was dependent on medications (药物) to enable him to survive.When he was five,he had a tube surgically(外科手术上) inserted in a vein（静脉）in his chest.This tube was connected to a pump,which he carried in a small backpack on his back.Medications were connected to this pump and were continuously supplied through this tube to his bloodstream. At times,he also needed supplemented oxygen to support his breathing.
