Presently we heard the sound of sliding boards, and an instant later a square had opened in the planks.

不久，我们听到木板滑动的声音， 片刻之后，木板上出现了一个正方形。

They provided the answer to the pioneers' need for a safe and sturdy home that an ordinary family could build quickly: they had dirt floors and sliding boards for windows.

他们满足了先驱者对普通家庭可以快速建造的安全坚固房屋的需求：他们有泥土地板和窗户滑动板。