2. this
     this 在介紹某人或某物時，指的是靠近自己的一方。
     A: Hi, Mr. Smith, This is my friend, Bill.
     B: Nice to meet you, Bill.
     C: Nice to meet you, Mr. Smith.
     This 在電話用語中指的是自己。
     A: Hello, may I speak to Miss Li?
     B: This is Miss Li speaking. (我就是李女士)
     which、that 、who、whom在定語從句中的替代用法
     1. which 在句中放指物的先行詞后或整個句子后，引導(dǎo)限定性定語從句或非限定性定語從句。
     She said I was lazy, which isn’t true.( which替代句子 She said I was lazy)
     This is the pen which was bought by my father. (which替代的是 the pen)
     2. that在句中放先行詞后，引導(dǎo)限定性定語從句。既可指物，也可指人。
     The book that she borrowed from the library was lost. ( that替代的是The book)
     The man that with a knife in his hand is a murderer. (that替代的是The man )