在气液色谱法中,为了改变色谱柱的选择性,下述可进行的操作是()
A.改变载气的种类
B.改变载气的速度
C.色谱柱的长度
D.改变固定液的种类
E.改变色谱柱的内径
参考答案:D
公路宽约80厘米。[ ]
(74) systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and (75) on the disk, and controlling peripheral devices such as disk drives and printers.
A.Operation
B.Operator
C.Operating
D.Operate