题目

More than its influence on health, not getting enough sleep can lead to car accidents or other mistakes. Here are what sleep researchers have found about how to sleep.How much sleep do we actually need?It is known that all of us naturally need no less than 8 hours of sleep per night. When we sleep below six hours per 24, we’re at an increased risk of health problems. Some of us think we can make up any of those hours lost during the week on the weekends. Suddenly there is no storage system for sleep in the brain.Can we train ourselves to need less sleep?As a study in 1964, a 17- year- old bo ________ milk is there in the glass? [　　] A． How much B． How many C． How often D． How long