单选题 — Excuse mc, are you waiting for the bus?
— Yes, I am. But the bus is so late.______, how can I get to No.1 Middle School?

【正确答案】 D
【答案解析】从整个语境中可以看出,所填部分为一独立成分,是引起所问问题的插入语,应用by the way,意思是“顺便问一下”。