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。
No one can plead ignorance of a subject any longer, for these are countless do-it-yourself publications.
由于出版了不计其数的教人自己动手做事的书报杂志,没有人再能说对某事一无所知。