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 first permanent picture was made by using_________
A. special paper
B. silver salt
C. common salt
D. a special metal
Questions 1 to 4 are based on the following conversation. At the end of the conversation, you will be given 20 seconds to answer the questions. Now listen to the conversation. How often is the bus scheduled to pass their stop
A. Every 21 minutes.
B. Every hour.
C. Every 30 minutes.
D. Every 9 minutes.