单选题
The vegetative forms of most bacteria axe killed by drying in air, although the different species exhibit pronounced differences in their resistance. The tubercle bacillus is one of the more resistant, and vibrio cholcra is one of the more sensitive to drying In general, the encapsulated organisms are more resistant than the non-encapsulated forms. Spores are quite resistant to drying; the spores of the anthrax bacillus, for example, will germinate alter remaining in a dry condition for years or more. The resistance of the pathogenic forms causing disease of the upper respiratory tract is of particular interest in connection with airborne infection, for the length of time that a droplet remains infective is a result, primarily, of the resistance of the particular microorganism to drying.
单选题
Tuberculosis is highly infectious because ______. A. spores are resistant to drying B. the causative organism is encapsulated C. droplets of sputum remain infective for a long time due to the resistance of the organisms to drying D. none of these
单选题
The passage uses the term "vegetative forms" to refer to ______. A. Plants that infest human habitations B. the fact that bacteria are really vegetables C. the growing stage of the bacteria as opposed to the dormant stage D. the difficulty in classifying the types of bacteria
单选题
According to the passage, the risk of infection from airborne microorganisms would likely be greater during a ______. A. heat wave B. time of high humidity C. windless period D. shortage of fuel oil
【正确答案】
B
【答案解析】文章一开头就交代了细菌在干燥的空气中难以存活“The vegetative forms of most bacteria are killed by drying in air，”反之，潮湿的空气下，其较易存活，传染性也就越强。A条件下，不利于其生存；C，D条件文中未提到。
单选题
It may be inferred from the passage that ______. A. bacteria can be most easily killed by removal of moisture B. drying out a house will eliminate the risk of airborne infection C. hot-air heating is better than steam heating because steam heating uses water D. none of the above