函数f(x)=sinx+2|sinx|,x∈[0,2π]的图象与直线y=k有且仅有两个不同的交点,则k的取值范围是( )。
1<k<3
病毒不同于衣原体的特点是()
A.能通过细菌滤器
B.对抗生素不敏感
C.可引起机体多部位感染
D.严格地细胞内寄生
E.在感染细胞内可形成包涵体
Not until the train pulled into the next station _____ her suitcase gone.[ ]
A. Mary had found
B. had Mary found
C. did Mary find
D. Mary found