He kept thinking of the question whether it was ____ for his father to change the habit of a life

time in such a short time.    [ ] 

A. possibly  

B. probable  

C. likely    

D. possible

为了提高测定低含量组分的灵敏度，通常选用待测元素的共振线作为分析线但当待测元素的共振线受到其他谱线干扰时，则选用其他无干扰的较灵敏谱线作为分析线。