(adv.) up to that time; 'they had not done any work theretofore'.
杰克逊整理
双语例句
Theretofore Gutenberg had had no assistants, but, on thinking the matter over, he decided that if he had a good workman with him he would have more time to study the art of printing. 鲁伯特·萨金特·荷兰.历史性发明.