一.首先我們來一起認識一下定語從句：
（1）定語
（2）定語從句：一個完整的句子，在一個更大的句子中，修飾名詞或代詞，充當定語。
（3）定語從句作用
當存在著多個同類人物、事物時（如上圖兩位女士），如果說得很籠統：
a1. I know the lady.
聽者仍不知道我們說的到底是哪位女士，這就需要我們透過更詳細的描述來指定。
a2. The lady is wearing a hat.
如果寫出來，我們可以把詳細資訊放到括號中。
a3. I know the lady (the lady is wearing a hat).
如果把括號中的the lady換成who，括號中的句子就成了一個定語從句，而括號外的部分，就成了主句。
a4. I know the lady who is wearing a hat.
定語從句的作用，顧名思義，就是透過一個從句，來“指定”前面提到的人、物等，具體說明是哪一個。
二. 定語從句的四要素
1. 四要素之間的關係
如：The man who lives next door is a doctor.
① 先行詞：the man ② 定語從句：who lives next door
The car that you lent to David broke down (拋錨).
① 先行詞：the car ② 定語從句：that you lent to David
三.who、that、which——在定語從句中作主語
1. 先行詞是人——選取who、that（常用who）
c1. The designer (設計師) is Sandy’s younger sister.
c2. The designer is talking.
c3. The designer (she is talking) is Sandy’s younger sister.
用who或that代替she/designer
c4. The designer who/that is talking is Sandy’s younger sister.
2. 先行詞是物——選取that、which（常用that）
f1. Joe loves reading those books.
f2. Those books have happy endings (結局).
f3. Joe loves reading those books (they have happy endings).
用that或which代替they/those books
f4. Joe loves reading those books that/which have happy endings.
四.whom、who、that、which——在定語從句中作賓語
關係詞在定語從句中作賓語時，仍舊放在從句之首，或者直接省略。
1. 先行詞是人——選取whom（who）、that
i1. The Jacksons are away on holiday.
i2. I want to visit the Jacksons.
i3. The Jacksons (I want to visit them) are away on holiday.
用whom/who/that代替them/the Jacksons
但要提到從句之首，或直接省略
i4. The Jacksons whom/who/that I want to visit are away on holiday.
i5. The Jacksons I want to visit are away on holiday.
先行詞是人、關係詞在定語從句中作賓語時，賓格的whom當然最“符合語法”，但在口語中很少用這個詞，而是用主格的who代替whom，或直接省略。
2. 先行詞是物——選取that、which
j1. Linda has found the keys.
j2. Billy lost the keys yesterday.
j3. Linda has found the keys (Billy lost them yesterday).
用that或which代替them/the keys，但要提到從句之首，或直接省略
j4. Linda has found the keys that/which Billy lost yesterday.
j5. Linda has found the keys Billy lost yesterday.
一.首先我們來一起認識一下定語從句：
（1）定語
（2）定語從句：一個完整的句子，在一個更大的句子中，修飾名詞或代詞，充當定語。
（3）定語從句作用
當存在著多個同類人物、事物時（如上圖兩位女士），如果說得很籠統：
a1. I know the lady.
聽者仍不知道我們說的到底是哪位女士，這就需要我們透過更詳細的描述來指定。
a2. The lady is wearing a hat.
如果寫出來，我們可以把詳細資訊放到括號中。
a3. I know the lady (the lady is wearing a hat).
如果把括號中的the lady換成who，括號中的句子就成了一個定語從句，而括號外的部分，就成了主句。
a4. I know the lady who is wearing a hat.
定語從句的作用，顧名思義，就是透過一個從句，來“指定”前面提到的人、物等，具體說明是哪一個。
二. 定語從句的四要素
1. 四要素之間的關係
如：The man who lives next door is a doctor.
① 先行詞：the man ② 定語從句：who lives next door
The car that you lent to David broke down (拋錨).
① 先行詞：the car ② 定語從句：that you lent to David
三.who、that、which——在定語從句中作主語
1. 先行詞是人——選取who、that（常用who）
c1. The designer (設計師) is Sandy’s younger sister.
c2. The designer is talking.
c3. The designer (she is talking) is Sandy’s younger sister.
用who或that代替she/designer
c4. The designer who/that is talking is Sandy’s younger sister.
2. 先行詞是物——選取that、which（常用that）
f1. Joe loves reading those books.
f2. Those books have happy endings (結局).
f3. Joe loves reading those books (they have happy endings).
用that或which代替they/those books
f4. Joe loves reading those books that/which have happy endings.
四.whom、who、that、which——在定語從句中作賓語
關係詞在定語從句中作賓語時，仍舊放在從句之首，或者直接省略。
1. 先行詞是人——選取whom（who）、that
i1. The Jacksons are away on holiday.
i2. I want to visit the Jacksons.
i3. The Jacksons (I want to visit them) are away on holiday.
用whom/who/that代替them/the Jacksons
但要提到從句之首，或直接省略
i4. The Jacksons whom/who/that I want to visit are away on holiday.
i5. The Jacksons I want to visit are away on holiday.
先行詞是人、關係詞在定語從句中作賓語時，賓格的whom當然最“符合語法”，但在口語中很少用這個詞，而是用主格的who代替whom，或直接省略。
2. 先行詞是物——選取that、which
j1. Linda has found the keys.
j2. Billy lost the keys yesterday.
j3. Linda has found the keys (Billy lost them yesterday).
用that或which代替them/the keys，但要提到從句之首，或直接省略
j4. Linda has found the keys that/which Billy lost yesterday.
j5. Linda has found the keys Billy lost yesterday.