The Great Wall winds its way _____ mountains _____ valleys and _____ deserts to the east.
--- I cannot find Mr. Smith. Where did you meet him this morning? --- It was in the hotel ____ he stayed.
The workers ______ the glasses and marked on each box “ This Side Up”
We _______ on this project for four hours. Let’s have a rest.
In organic farming, natural waste from animals are made use of ________ the fields.
In the examination, anyone ___________ will be punished.