--- Why were you so late for work today？
--- to the office was very slow this morning because of the traffic.
ADriving
B. I drove
C. To drive
D. That I drove
网友回答
(答案→)A. Driving
B. I drove
C. To drive
D. That I drove
解析：考查动名词做主语用法。本题中的动名词driving to the office做为句子的主语，动名词做主语指经常性，习惯性的行为。B项不能做主语；C项不定式做主语是指一次性的行为；D项是主语从句做主语，但是意思不句意不配。句意：—为什么你今天迟到了？—因为交通高峰期，所以驾车去办公室里很慢的。故A正确。