4.Which cancer risk is the lowest among all the four kinds of cancer mentioned in the passage?
A. Oral cancer
B. Laryngeal cancer
C. Pharyngeal cancer
D. esophageal cancer
查看答案
一般而言,验证样本占总样本量的比例为( )
A. 0.1
B. 0.15
C. 0.2
D. 0.25
E. 0.05
是什么东西
A. 1
B. 2
C. 3
D. 4