In January the penny post was established, covering the whole country: in its first year it would double the volume of letters written.
一月，遍布伦敦的邮局建成了，第一年的书信量就翻了一番。
2
In order to reduce energy consumption in greenhouse, the underground heat storage system with double-film covering was designed based on the plant physiology.
针对温室加温能耗大的突出问题，设计了双层覆盖温室地下蓄热系统。
3
The best is double plastic membrane cover, although more expensive than plastic covering layer higher, but the heat preservation effect is good.