This macro code expands out to the same two calls to extend shown in Listing 2 and Listing 3.

此宏代码扩大到要extend的两个调用，如清单2和清单3中所示。

youdao

This macro code expands out to the same two calls to extend shown in Listing 2 and Listing 3.

此宏代码扩大到要extend的两个调用，如清单2和清单3中所示。

youdao