The doctor performed an operation on him as soon as he was sent to the hospital.
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We must take some measures to control the pollution.
He has ________ on his farm.
A. 20 head of cattles
B. 20 heads of cattles
C. 20 heads of cattle
D. 20 head of cattle
下列选项中,()也称主次图,是直方图与折线图的结合,直方图用来表示属于某项目的各分类的频次,而折线点则表示各分类的累积相对频次。
A. 趋势图
B. 柱状图
C. 排列图
D. 控制图