罗马成为地中海的霸主是在[ ]
A．公元前6世纪
B．公元前5世纪
C．公元前2世纪
D．公元2世纪
答案：C
Which of the following statement about the following frequency distribution is FALSE（）
A. The cumulative absolute frequency of the third interval is 50.
B. The cumulative absolute frequency of the fourth interval is 30.
C. The return internals are mutually exclusive.
