计算机的应用可以分为几个层次,相对于计算机系统而言它们是( )
A.计算机操作,文字录入等
B.用处理日常事物,处理报表
C.硬件维修,连接处理
参考答案:C
18.______ everyone knows, John has made his promise to his parents ______ he will never play computer games again.
A.As; which
B.As; that
C.It; that
D.It; which
海上求生过程中,求生的三个要素并非完全孤立存在的。()