题目

阅读下面的短文，按照句子结构的语法情况和上下文连贯的要求，在空白处填入一个适当的词或用括号中所给词的正确形式填空，每空不超过两词。 This is a map ournew school. (go) into the school from the gate, and you can see a verybig . Students can play there. Theoffice (build) is in front of the playground. (we) teacherswork there. The library is the office building and the dining hall.After meals(饭后), students can (go)to the library to read books. They can also go to the garden to rest. Our classroombuilding with twenty classroo（（本小题满分12分）如图，已知在直四棱柱中，，，．（1）求证：平面；（2）求二面角的余弦值．