We'll get there at eight, but they _____.[ ]

A. aren't

B. didn't

C. won't

D. don't

下列不属于X线管构造参数的有（）

A.阳极靶面倾斜角度

B.灯丝尺寸

C.工作温度

D.最高管电压

E.阳极转速