男,45岁。CT示腰4椎体骨小梁稀少、增粗,呈颗粒样,骨皮质未见破坏,诊断为()
A.骨髓瘤
B.骨质软化
C.转移瘤
D.血管瘤
E.骨质疏松
参考答案:D
At the meeting they discussed three different _____ to the study of mathematics. [ ]
A. approaches
B. means
C. methods
D. ways
将一组数据经过标准化处理后,其平均值为1、方差为0。