what about ——（go）out for a walk?

going
[知识点分析]
1。about是一个介词,介词后加动词,要用动词的动名词形
式,即doing形式。
2。What about doing sth。这是一个提建议的句子,
“去做……事,怎么样?”
What about doing sth。= How about doing sth。