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, have you considered using the lab in your free class? I suggest you ask Mr. Wu.
噢,你是否考虑过在自习课上利用这个实验室?我建议你问问吴先生。