【简答题】The best start-up ideas are often the st. But entrepreneurs often need to experiment ________business models as their ventures grow. For young retail companies, ______ of the biggest challenges ...
【单选题】听力原文: The classic case in medical history of a typhoid carrier is that of Mary Mallon. During a New York typhoid epidemic she was found working as a cook and thus very readily spread the disease to ot...