But the realities of decision making, as I have tried to show earlier in this chapter, are not so readily pinned down. A: 弄明确 B: 钉住

利用CSS表现XML时，如果我们希望元素内容滚动时，元素的背景图像不随之滚动，而是附加于窗口，这时需将“background-attachment”属性的值设置为（）。 A: scroll B: pinned C: fixed D: fix

Which is the correct description of a pinned buffer in the database buffer cache（） A: The buffer is currently being accessed. B: The buffer is empty and has not been used. C: The contents of the buffer have changed and must be flushed to the disk by the DBWn process.  D: The buffer is a candidate for immediate aging out and its contents are synchronized with the block contents on the disk.