超市里有各种各样的商品供人们挑选.
Thereareallkindsofgoodsforpeople_________________inthesupermarket.
城市里的人们越来越忙,因此他们感到越来越紧张.
Peopleincitiesare______________,sotheyfeel___________nervous.
很难想象长城是怎样建成的.
_____________howtheGreatWallwasbuilt.
世界人口正在迅速增长.
Thepopulationoftheworld___________________quickly.