管理是分层次的,所以医院领导不能越俎代庖,科室的工作应交科室领导负责。()
参考答案:对
—________did your uncle leave his hometown?
—He ________ for nearly twenty years.
A.When; has left
B.When; has been away
C.How long; has left
D.How long; has been away
一般容积大、水深深的湖泊,通常水温的垂向分布有三个层次,上层、中间层(温跃层)和下层,其中溶解氧浓度最高的是( )。
A.上层 B.中间层C.下层 D.三层溶解氧浓度均接近