The development of laryngeal cancer is most clearly linked to which of the following factors

A. High-fat, low-fiber diet.
B. Alcohol and tobacco use.
C. Low socioeconomic status.
D. Overuse of artificial sweeteners.

麦汁总氮的测定中，所要用的主要化学试剂有下列（）。

A、氢氧化钠、盐酸、酚酞

B、硫酸、硫酸铜、甲基红 

C、盐酸、硫酸钾、结晶紫

D、硫酸、硼酸、溴甲酚绿、氢氧化钠