比較下面的考題：
1. This is the room _________I lived ten years ago.
A. that B. where C. who D. what
2. This is the room _________I lived in ten years ago.
A. that B. where C. who D. what
3. This is the room _________I bought ten years ago.
A. that B. where C. who D. what
4. This is the room _________I visited ten years ago.
A. that B. where C. who D. what
5. This is the room _________I was born ten years ago.
A. that B. where C. who D. what
第1題選B，因為 live 是不及物動詞，它無需接賓語;第2題選A，因為雖然 live 不及物，但live in 卻是及物，它應有自己的賓語;第3、4題也應選A，因為 buy 和 visit均為及物動詞，它們應有自己的賓語;第5應選B，因為 be born 無需有自己的賓語。
四、誤認為逗號后一定是非限制性定語從句
有的同學一看見逗號，就以為一定要選which而不選that，但問題是有時根本就不是定語從句。如：
1. If a book is in English, _________ means slow progress for you.
A. as B. which C. what D. that
2. When I say two hours, _________ includes time for eating.
A. as B. which C. what D. that
以上兩題均應選that，而不能選which，因為它們根本不是定語從句。之所以選that，是因為句中已有if和when引導的狀語從句，逗號后為主句，that為主句主語。
