—I do enjoy my present job as an engineer.

—Well，I would also be an engineer if I       my major when I was at college.

A．could have changed

B．should change

C．hadn't changed

D．were to change

类白血病反应的特点是（）

A.外周血白细胞>50×10⁹／L

B.外周血出现幼稚细胞，NAP活性增高

C.骨髓中幼稚粒细胞增高

D.脾显著肿大

E.Ph’染色体阳性