Questions 18 to 20 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions. Now listen to the passage. Why did the lower-class white people in the United States treat Chinese immigrants with hostility
A．Because they didn’t understand their language. B．Because they saw them as a source of threat to their jobs. C．Because they were arrogant people. D．Because they had very different appearances.