欲用统计图表示某市1980年和1990年痢疾、肝炎、流脑、麻疹和腮腺炎5种传染病的构成情况,应用()。
A.圆图或百分比条图
B.线图
C.直方图
D.条图
E.散点图
参考答案:A
Many children, ________ parents are away working in big cities, are taken good care of in the village.[ ]
A. their
B. whose
C. of them
D. with whom
钢制离子交换器内壁如不采取防腐措施易引发树脂中毒。()