Hedrovefastandarrivedanhour_____ofschedule.
B
ahead of “提前，预先 ” ，ahead of schedule “比规定时间提前 ”，正合题意。本句意 为“他开得很快， 比规定时间早到了 1 小时。”in advance “ 事先，提前”，后面不跟介词。 in front of “ 在⋯⋯前面 ”，表示位置，所以此处不合题意。
Children who are over-protected by their parents may become_____.
My wallet is nowhere to be found.I_____it when I was on the bus.
_____all the representatives still not there ，the meeting was postponed for several hours.