SOX is an alternative syntax for (71) . It is useful for reading and creating XML content in a text editor. It is then easily transformed into proper XML. SOX was created because developers can spend a great deal of time with raw XML. For many of us, the popular XML (72) have not reached a point where their tree views, tables and forms can completely substitute for the underlying. (73) language. This is not surprising when one considers that developers still use a (74) view, albeit enhanced, for editing other languages such as Java. SOX uses (75) to represent the structure of an XML document, which eliminates the need for closing tags and a number of quoting devices. The result is surprisingly clear.

A．tree

B．text

C．program

D．graphic

建筑钢材的性能指标主要有哪些？