[单项选择]

Questions 14 to 17 are based on the following passage. At the end of the passage, you will be given 20 seconds to answer the questions. Now, listen to the passage.

The general tone of the passage is one of
A. annoyance.
B. explanation.
C. deduction.
D. complaint.

Passage Two
The modern age is an age of electricity. People are so used to electric lights, radios, televisions, and telephones that it is hard to imagine what life would be like without them. When there is a power failure, people grope about in fickering candlelight, cars hesitate in the streets because there are no traffic lights to guide them, and food spoils in silent refrigerators.
Yet, people began to understand how electricity works only a little more than two centuries ago. Nature has apparently been experimenting in this field for millions of years. Scientists are discovering more and more that the living world may hold many interesting secrets of electricity that could benefit humanity.
All living cells sent out tiny pulses of electricity. As the heart beats, it sends off pulses of electricity that can be measured and recorded at the surface of the body. When the pulses are recorded, they form an electrocardiogram, which a doctor can study
A. To warn the reader to stay away from them.
B. To compare their voltage to that used in houses.
C. To give an example of a living electrical generator.
D. To describe a new source of electrical power.

男，26岁，左腰腿痛1个月加重5天，直腿抬高试验及加强试验阳性，左拇趾背伸肌力减弱，X线平片示腰椎屈度变直，轻度退行性改变。

绿色食品标准由以下几个部分构成（）。
①绿色食品产地环境标准，即《绿色食品产地环境技术条件》；
②绿色食品生产技术标准；
③绿色食品产品标准；
④绿色食品包装、贮藏运输标准；
⑤生产员工健康标准。