总结：当先行词指人充当（ ）时，可以用关系代词（ ）或（ ），但whom 比who要更正式。此时的关系代词可以（ ）。

3．Whose

Do you know the boy whose father is an engineer?

He lives in a house whose windows face south.

总结：当先行词在从句中充当（ ）指（ ）或（ ）用关系代词whose.

4. that

I didn't know the man（that）you mentioned.

总结：关系代词that 可以指人也可以指物。在从句中充当（ ）和（ ），充当（ ）时可以省略。

5. which

The pen (which) my uncle gave me is expensive.

Children like books which have good pictures.

总结：关系代词which 用来指（ ），在从句中可作（ ）或（ ），作（ ）时可省略。

　　课堂训练

Read the article on Page 9 and underline the attributive clauses.