Which of the following best describes the relationship between the two men

A．Smith gives Brown money.

B．Smith is faithful to Brown.

C．Brown’s noble character makes him faithful to Smith.

D．Brown is faithful to Smith because the latter often praises him.

下列关于实验安全的说法错误的是（　　）

A．一切能产生有毒气体的实验均不要进行

B．易燃易爆物不能跟其它物质混存

C．不得尝任何化学药品的味道

D．化学实验室必须备有灭火器等防火器材