.Lesson 01 A Puma at large 逃遁的美洲狮Special difficulties 难点Exercises A1. at/for 2. to 3. to 4. in 5. onExercises B1. He is the man we have heard about so much.2. The shelf you put those books on has collapsed.（vi.倒塌, 崩溃, 瓦解）3.Whom did you receive a letter from 特殊疑问句中whom 不能省略（本句）。定语从句中Which以及指代人的做宾语的Whom, 在非正式用法当中可以省略。省略时，介词不能前置到关系代词Whom, Which前，只能用于非固定的动词短语后面。固定的动词短语look for：寻找（去掉for后look没有寻找的意思，所以介词for不能前置）非固定的动词短语look at：注视live in：居住（
