题目

. 第二部分 阅读理解（共分两节,满分45分） 阅读理解（共20小题；每小题2分，满分40分） 阅读下列短文，从每题所给的四个选项A、B、C、D中，选出最佳选项，并在答题卡上将该项涂黑。 Nate suffered a hard blow when he lost his job. His boss had spoken rudely, “Your services are no longer needed.”Nate left the building filled with despair. By the time he reached home, he was in deep sadness. When he entered his house, he blurted out to his wife Sophia,“I lost my job. I am a complete, utter failure.”A tense silence followed. T已知正四棱柱ABCD-A′B′C′D′的外接球直径为6，底面边长AB=1，则侧棱BB′与平面AB′C所成角的正切值为 ．