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。
Well, you just need lots of practice. The more you listen to English, the easier it becomes.
噢,你需要大量的练习。英语你听的越多,就越容易听懂。