a barrel for collecting rainwater的用法和样例：
- Natural lighting and air-conditioning, rainwater recycling model on the roof for collecting rainwater to re-use, the miraculous Water Resources Education Center will open soon!
- The boys had a craze for collecting stamps.
- A sturdy cylindrical container for storing liquids; a barrel.
- Oil on the 3 Sep traded at about $108.93 a barrel for US crude, down 26 per cent from its peak over the summer.
- He made a barrel with staves by himself.