Fifty-litre carboy would be the most economical size. Carboys may be retained without charge for two months.
50升的瓶子应是最经济的尺码,这些瓶子可免费保存两个月。
This may be illustrated by comparing the position of a nation with that of a private business enterprise.
把国家的状况同私人企业的状况加以比较,就可以看清这个问题。