题目

Since my family were not going to be helpful, I decided I would look for one job by myself and not tell them about it till I'd got one.                 I had seen an agency advertised in a local newspaper. I rushed out of the   21    in search of it. I was wildly excited, and as    22   as if 1 were going on the stage. Finding the    23   quite easily, I ran breathlessly through a door which said Enter without knocking, if you please. The simple atmosphere of the office    24   me. The woman looked carefully at me   25   through her glasses, and then �如图，正方形ABCD和四边形ACEF所在的平面互相垂直，CE⊥AC，EF∥AC，AB=，CE=EF=1．（Ⅰ）求证：AF∥平面BDE；（Ⅱ）求证：CF⊥平面BDE；（Ⅲ）求二面角A-BE-D的大小．