单项选择题

Questions 11 to 14 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.

What is the main idea of the passage

A.Fear and worry are dangerous.
B.Fear and worry can sometimes help us.
C.Fear and worry will cause damage unless kept under control.
D.No one can control fear and worry.