Which of the following statements is TRUE（）

A. When a rating agency downgrades a security, the bond’s price usually falls.

B. Technical default usually refers to the issuer’s failure to make interest or principal payments as scheduled in the indenture.

C. Default risk is important because if a bond issuer defaults, the bondholder likely loses his entire investment.

触媒使用初期，操作上一般采用（）操作。

A、低温

B、高负荷

C、超负荷生产

D、高温