关于病毒叙述正确的是( )
A:病毒具有完整的细胞结构
B:病毒能够独立的生活
C:病毒只能在活细胞中繁殖
D:病毒对人体都是有害的
He had wanted to write ____children's book for many years, but one thing or another always got in _________ way.