He usually waves ___________ goodbye.A. they B. their C. them
以下说法错误的是( )
设全集为,集合,则( )
已知函数,若互不相等,且满足,则的取值范围是 ( )
已知函数是偶函数,且函数在[0,2]上是单调减函数,则( )
已知函数满足,且∈[-1,1]时,,则函数的零点个数是( )