基本的關係代名詞和六大使用原則
http://www.learnerhall.org/2012/10/blog-post3002.html
▍基本的關係代名詞
2️⃣ that 關係代名詞前不可有逗號，也不可放介係詞。
例：我還沒見過 John 暗戀的那個女孩。 ( have a crush on N：暗戀…)
(1) I haven’t met the girl that John has a crush on. ✅
(2) I haven’t met the girl whom John has a crush on. ✅
(3) I haven’t met the girl John has a crush on. ✅
(4) I haven’t met the girl on whom John has a crush. ✅
(5) I haven’t met the girl on that John has a crush. (x)
(6) I haven’t met the girl on John has a crush. (x)
3️⃣ that 關係代名詞不能當「所有格」關代使用。
例：我爸媽住在那屋頂是紅色的房子。
(1) My parents live in the house whose roof is red. ✅
4️⃣ 先行詞包括人和物時，只能用 that 關係代名詞。
例：被困在著火的房子裡的老人和狗，已被救出。
5️⃣ who 或 which 開頭的疑問句，句中關係代名詞必須用 that，才可避免和疑問詞 who / which 混淆。
例：剛剛打電話來的那個女人是誰？
(1) Who is the woman that just called? ✅
(2) Who is the woman who just called? ❎
6️⃣ 先行詞前有「最高級」、「序數」、the only、the very、the same 時，只能用 that 關係代名詞。
例：這是我看過最棒的一部電影。
(1) This is the best movie that I have ever seen. ✅
(2) This is the best movie which I have ever seen. ❎
| 先行詞 | 主詞 | 受詞 | 所有格 |
| 人 | who | whom | whose |
| 事物 | which | which | of which/ whose |
| 人、事物 | that | that | 無 |
依關係代名詞所代替的名詞在句中所處位置，可分成「主格」、「受格」、「所有格」；且就該名詞屬性分成「人」和「事物」兩類。
▍使用關係代名詞時應注意的事項
1️⃣「受詞」性質的關係代名詞可省略，但若受詞性質的關係代名詞前有「介係詞」或「逗號」則不可省。
例：媽媽昨天買的麵包很好吃。
(1) The bread which Mom bought yesterday is delicious. ✅
(2) The bread that Mom bought yesterday is delicious. ✅
(3) The bread Mom bought yesterday is delicious. ✅
1️⃣「受詞」性質的關係代名詞可省略，但若受詞性質的關係代名詞前有「介係詞」或「逗號」則不可省。
例：媽媽昨天買的麵包很好吃。
(1) The bread which Mom bought yesterday is delicious. ✅
(2) The bread that Mom bought yesterday is delicious. ✅
(3) The bread Mom bought yesterday is delicious. ✅
因先行詞為 bread，連接兩句時需要「物／受詞性質」的關係代名詞，故 (2) that 和 (1) which 皆可。又受詞性質的關係代名詞可省略，故 (3) 省略關係代名詞也對。
2️⃣ that 關係代名詞前不可有逗號，也不可放介係詞。
例：我還沒見過 John 暗戀的那個女孩。 ( have a crush on N：暗戀…)
(1) I haven’t met the girl that John has a crush on. ✅
(2) I haven’t met the girl whom John has a crush on. ✅
(3) I haven’t met the girl John has a crush on. ✅
(4) I haven’t met the girl on whom John has a crush. ✅
(5) I haven’t met the girl on that John has a crush. (x)
(6) I haven’t met the girl on John has a crush. (x)
因先行詞為 the girl，介係詞 on 後方需搭配受詞，故連接兩句時需要「人／受詞性質」的關係代名詞，(1) that 和 (2) which 皆可。
又受詞性質關係代名詞可省，故 (3) 省略關係代名詞也對。
也可將介係詞放在關係代名詞前，(4) 正確。
因 that 關係代名詞前不可有介係詞，故 (5) 是錯誤的句子。
受詞性質的關係代名詞前有「介係詞」時，關係代名詞不可省略，故 (6) 是錯誤的句子。
3️⃣ that 關係代名詞不能當「所有格」關代使用。
例：我爸媽住在那屋頂是紅色的房子。
(1) My parents live in the house whose roof is red. ✅
(2) My parents live in the house that roof is red. ❎
因先行詞為 the house。這裡的屋頂指的是「房子的」屋頂，故連接兩句時需要「物／所有格性質」的關係代名詞 whose。
that 關係代名詞不具所有格性質，故 (2) 是錯誤的寫法。
4️⃣ 先行詞包括人和物時，只能用 that 關係代名詞。
例：被困在著火的房子裡的老人和狗，已被救出。
(1) An old man and his dog that were trapped in the burning house were saved. ✅
(2) An old man and his dog which were trapped in the burning house were saved. ❎
(3) An old man and his dog who were trapped in the burning house were saved. ❎
(2) An old man and his dog which were trapped in the burning house were saved. ❎
(3) An old man and his dog who were trapped in the burning house were saved. ❎
因先行詞為 an old man and his dog，有人也有物，故連接兩句時只能用既可代替人也可代替物的關係代名詞 (1) that。
which 關係代名詞只能代替「物」the dog， 不能代替「人」an old man，故 (2) 是錯誤的句子。
who 關係代名詞只能代替「人」an old man，不能代替「物」the dog，故 (3) 是錯誤的句子。
5️⃣ who 或 which 開頭的疑問句，句中關係代名詞必須用 that，才可避免和疑問詞 who / which 混淆。
例：剛剛打電話來的那個女人是誰？
(1) Who is the woman that just called? ✅
(2) Who is the woman who just called? ❎
因已有疑問詞 who，為避免混淆，不可用關係代名詞 who 連接兩句，(2) 為錯誤的句子，需將 who 改成 (1) 關係代名詞 that。
6️⃣ 先行詞前有「最高級」、「序數」、the only、the very、the same 時，只能用 that 關係代名詞。
例：這是我看過最棒的一部電影。
(1) This is the best movie that I have ever seen. ✅
(2) This is the best movie which I have ever seen. ❎
因先行詞為 the best movie，當中包含最高級 the best，所以只能用 (1) 關係代名詞 that，不能用關係代名詞 which，(2) 是錯誤的句子。
