What did the Blacks da before__to the airport A they start B starting Cstarted Dthey starting
问题描述：
What did the Blacks da before__to the airport A they start B starting Cstarted Dthey starting
答
B
before后面要么接个从句,要么用动词ing或者动词ed
应为本句有did,是过去时态,排除A,应改为they started
D不对,应该改为their starting
他们和出发是主动的关系,所以用starting