确诊白血病的最重要的实验手段是（）
A.外周血白细胞计数
B.骨髓细胞学检查
C.浆膜腔穿刺
D.外周血白细胞分类
E.淋巴结穿刺
参考答案：B
English for more than six years, he can speak and work very well with that businessman from England.
A．To have learned
B．To learn
C．Learning
D．Having learned
