书名：怪物讲师教学团队的多益3回全真模拟试题
版本：2/e
页数：p.23 第122题
题目：
Items____ behind by passengers in the cabin will be retained at the Lo
st&Found office at the arrival terminal for three business days before being t
ransferred to the local law enforcement.
(A) having been left
(B) have been left
(C) that have left
(D) are left
疑问：为什么是A而不是B