____yesterday morning they flew to Beijing for a trip.A.in B.on C.at D.不填
问题描述：
____yesterday morning they flew to Beijing for a trip.A.in B.on C.at D.不填
答
D
Yesterday morning they flew to Beijing for a trip.
Yesterday morning 时间状语 ,不用加介词,也可以放在句后,昨天上午.翻译：他们昨天上午飞去了北京度假.