题目

The trouble with the TV weather report is that it brings out the worst news to all of us. The other evening I was watching my   26   on the late night news, and he said, “A cold wind is coming down from Canada and will sweep across the Great Plains, carrying   27   temperatures, snow and ice.” “What are you smiling at?” my wife wanted to know. “We are   28   ” I said. “But the people in the Great Plains are Americans too.” “They’re   29   to it.” I replied. “This kind of weather is soft to them.” The weatherman was waving his hands all over the  6．已知四面体ABCD的棱长均为$\sqrt{2}$，则下列结论中错误的是（　　）A．AC⊥BDB．若该四面体的各顶点在同一球面上，则该球的体积为3πC．直线AB与平面BCD所成的角的余弦值为$\frac{\sqrt{3}}{3}$D．该四面体的体积为$\frac{1}{3}$