单选题
- A. Cold.
- B. Viruses.
- C. Infection.
- D. Wet.
单选题
- A. When they are working in the isolated Arctic regions
- B. When they are writing reports in terribly cold weather
- C. When they are free from work in the isolated Arctic regions
- D. When they are coming into touch again with the outside world
单选题
- A. Cold and wet are not responsible for catching colds.
- B. No one caught a cold even they were kept cold and wet.
- C. A cold virus caused a cold in volunteers.
- D. h was easier to catch a cold indoors in winter.