47．B 根据语境when there was a knock on the door判断，这里指Josie 去开门，answer在此表示“应门声开门”。
48．A 根据后面的信息词some water和信息句when she returned to the living room可以推测，Josie是去厨房找水。
49．C gone在此表示“不见了”。
50．A 语境found Sarah sleeping in her bed强调的是结果，因此in the end(最终)符合语境。
51．D 根据后面的语境because Sarah couldn't...the stairs without help because they were very steep可以推测，这是不可能发生的事情。
