构成肺门阴影最主要的结构是（）
A.肺动脉、静脉
B.神经
C.主支气管
D.肺组织
E.淋巴结
参考答案：A
测得白细胞计数为8.5×109/L，而报告单上写的是5.8×109/L，这种差错是（）
A.系统误差
B.偶然误差
C.过失误差
D.方法误差
E.总误差
— does your mother exercise?
—She hardly ever exercises. She doesn't like sports.[ ]
A. When
B. What sports
C. What
D. How often
