心脏最常见的良性肿瘤是（）
A.脂肪瘤
B. * * 状瘤
C.黏液瘤
D.弹力纤维瘤
E.横纹肌瘤
参考答案：C
—Where is my pen? Have you seen _____?
—Oh, sorry. I have taken _____ by mistake. [ ]
A. it; yours
B. them; his
C. it; mine
D. them; hers
频数分布表中落在某一特定类别的数据个数称为（）
A.组数
B.频数
C.众数
D.中位数
