【题目】A high official will come and explain ______ what the country has done to ensure to make the Football World Cup the best-ever game.
A.in length
B.at length
C.by length
D.to length

【答案】B
【解析】at length指“详细地”，此处指这位官员将对国家所做的事情做一个详细的解释。 in length意为“在长度上”；by length指以长度为度量；没有to length这种搭配。 故选B。