我把一本厚字典当作门挡，防止门自己关上。

I used a thick dictionary as a ___doorstop to prevent the door from closing by itself.

我们在门下面放了一个门挡，这样猫就能自由进出。

We placed a ___doorstop under the door so the cat could come and go freely.

这本词典厚得都能当门挡用了。

This dictionary is so thick it could work as a ___doorstop.