Which of the following is NOT an example of event risk（）

A. An interim South American government imposes restrictions on the outflow of capital.

B. The U. S. Food and Drug Administration (FDA) determines that a biotech company’s flagship product is harmful to consumers and cannot be marketed.

C. A corporation calls a large bond issue.

气块在作铅直运动时，其温度随高度的变化曲线称为（）。