题目

Some people will do just about anything to save money. And I am one of them. Take my family’s last vacation. It was my six-year-old son’s winter break from school, and we were heading home from Fort Lauderdale after a weeklong trip. The flight was overbooked, and Delta, the airline, offered us $400 per person in credits to give up our seats and leave the next day. I had meetings in New York, so I had to get back. But that didn't mean my husband and my son couldn't stay. I took my nine-month-old and took off for home. The next day, my husband and son were offered more credits to tak(徐州，2006)将两只用于医学研究的小白鼠分别放入A、B两个瓶中，A瓶内装有CO和的混合气体，B瓶内装有气体，拧紧瓶盖，结果两只小白鼠很快都死了．造成小白鼠死亡的主要原因是：A瓶 ___________________________________；B瓶____________________．