Questions 11 to 18 are based on the conversation you have just heard.

单项选择题A．They can buzz in to kill.B．They can hear the dry plants’ cries.C．They can imitate the plants’ crying.D．They can attack healthy plants in dry, hot weather.

单项选择题A．To maintain stable group relationship.B．To give orders and see to the attainment of group goals.C．To offer sympathy for group members in difficulty.D．To smooth tension and conflict among group members.