题目内容：

SECTION C (15 points)

Directions: Complete the following passage by using ONE word that best fits the context.

Or use the proper form to fill in the form.

Many years ago, when I worked as a volunteer at Stanford Hospital, I got to know a little girl ___46__ Liz who was suffering from a rare and serious disease. Her only chance of recovery appeared to be a blood transfusion（输血） ___47__ her 5-year-old brother, __48_ had miraculously survived the same disease and had developed the antibodies needed to fight the ___49_(ill).

The doctor explained the situation to her little brother, and asked the boy if he would be willing to give his blood to his sister. I saw him hesitate for a moment ___50__ taking a deep breath and saying, “Yes, I’ll do it __51_ it can save Liz.”

___52_ the transfusion progressed, he lay in bed next to his sister and smiled, as we all did, ___53(see) the color returning to her cheeks. Then ___54__ face grew pale and his smile faded. He looked up at the doctor and asked with a trembling voice, “Will I start to die right away?”

Being young, the boy had___55_(understand) the doctor; he thought he was going to have to give his sister all of his blood.