单项选择题


Questions 11 to 13 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.

Which of the following might best express the main idea of this passage

A.Advertising performs a useful service to the community.
B.All advertisements are useful.
C.Advertising makes a great contribution to our wealth.
D.Qualified products need to be advertised.