在没有楔形板的情况下,早期声门癌放疗首选的射线类型是()。
A.10MVX射线
B.6MVX射线
C.4MVX射线
D.60Coγ射线
E.电子线
参考答案:C, D
A certain percent of your salary is ________ by the employer as insurance payments. [ ]
A. kept away
B. kept out
C. kept up
D. kept back
什么叫岩浆岩?按其形成的环境可分为哪几类?