It is well known to us that Zhai zhigang is the first Chinese astronaut ___in space.walk的适当形式
问题描述：
It is well known to us that Zhai zhigang is the first Chinese astronaut ___in space.walk的适当形式
to walk 为什么
答
be the first + n.to do sth.这是一个固定的搭配.所以填to walk.