单选题 In theory, the journey ought to take three hours, but in practice it usually takes four because of roadworks.

【正确答案】 C

【答案解析】theoretically理论地；factually事实上；in practice实际上，实践中。该句意思是“从理论上讲，这次旅程需要花3个小时；实际上，由于道路施工，往往要花4个小时”。