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。
In all the less controversial fields, like the study of cacti or termites or the nature of nebulae,
在一切争议较小的领域里,如对仙人掌、白蚁或星云性质的研究,