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。
I had forgotten all about the snails when Robert suddenly said that I must stay to dinner.
我把蜗牛的事已忘得一干二净,罗伯特突然提出一定要我留下来吃晚饭,这才提醒了我。