题目

 It was about the third week in June last year. My 15-year-old son had already settled into his summer routine：Go to   __1__   at 2 a. m. and wake up at 1 p．m. only to get back on his computer to play computer games  __2__  dinner. It was the middle of the   __3__  when the sound of his computer games woke me up again. I couldn't  __4__  that any more and decided it was time for him to get a summer job. I got on the computer and found a lifeguard certification class that   __5__  the next day, and a company that   __6__  teenagers to guard their pools. From tha下列物质属于纯净物的是（ ）A. 普通玻璃 B. 空气 C. 漂白粉 D. 干冰