Mothers have been warned for years that sleeping with their newborn infant is a bad idea, because it increases the risk that the baby might die unexpectedly during the night.
2016年6月六级真题(第一套)听力 Section B
柯林斯高阶英汉双解学习词典释义
ADJ-GRADED
想不到的;未预料到的;意外的
If an event or someone's behaviour is unexpected, it surprises you because you did not think that it was likely to happen.