A:as soon as, finding
B:immediately, to find
C:the moment, fine
D:when, found
一列数a1,a2,a3,…满足条件:a1= 12 ,an= 11−an−1 (n≥2,且n为整数),则a2016=____.
下列实例中,属于光的折射现象的是( )