Directions:In this section, you will hear
3 short passages. At the end of each passage, you will hear some questions. Both
the passage and the questions will be spoken only once. After you hear a
question, you must choose the best answer from the four choices marked A), B),
C) and D).
Passage One Questions 26 to 28 are bused on the passage you have just
heard.
A．To develop a greater resistance. B．To increase the spread of infections. C．To create a good environment. D．To increase being infected.