Complete the following sentence with a (compound) word derived from the one(s) given in bracket.
It is said that one in five road accidents in the past three months is caused by the driver falling （ ） at the wheel.(sleep)
【正确答案】：ASLEEP
【题目解析】：
根据前文falling，fall有两种意思，意为掉落的时候为不及物动词；意为进入某种状态时为系动词。根据意思，这里fall并不是掉下去的意思，所以为系动词，空格处应该填形容词，sleep的形容词为asleep睡着的。fall asleep，睡着，入睡。句意：据说，过去三个月中，五分之一的交通事故是由司机在驾驶时睡着造成的。