The seat goes back into the wall where it is washed and blow-dried.

使用後馬桶會縮進牆裡, 並在那裡洗淨吹乾。

上列句中的where為關係副詞, 即等於in which, 修飾其前的名詞the wall。

where作關係副詞時, 其所引導的形容詞子句只用來修飾表地方的名詞, 此時where即等於"介詞in/on/at + 關係代名詞which", 若其前表地方的名詞為大地方 (如國家、城市、區域等) 或表內部 (在……之內) 時, 介詞用in; 若表示在某物之上時, 介詞用at; 若地方表外在 (在……上面) 時, 則介詞用on。

例: That is the restaurant where Ted first met Paula.

                                  = in which

  　(那就是泰德初次遇見寶拉的餐廳。)

  　I went to the station, where I ran into a good friend of mine.

                                  = at which

  　(我到了車站去，在那兒我見到一位老友。)

  　That is the hilltop where our school is located.

           　             = on which

  　(我們學校就是座落在那個山頂上。)

注意:

關係副詞除了where外, 尚有when、why、how三個:

a. when用以修飾表時間的名詞。

例:The exam took place at 3 p.m., when all the students were

                                 = at which

  　already very tired.

  　(考試在下午三點舉行, 那時所有的學生都已經很累了。)

b. why只用以修飾the reason (理由)。

例: I don't know the reason why Molly was fired.

                       = for which

  　(我不知道茉莉被開除的原因。)

c. how只用以修飾the way (方式、方法), 但使用時, the way之後的how一定要省略, 如不省略反而會成為贅述, 但我們 亦可省略the way, 而使用how。

　(每個人都喜歡他唱歌的方式。)

When it does, you'd better be ready or your face will be red!

當門自動打開時, 你最好已經辦完事, 不然你可要臉紅了！

上列句中的it乃指前句中的the door, 而does則代替前句中的動詞opens, 此處用it和does乃為避免相同詞類的重複之故。

　you'd better...　　你最好……

= you had better...

had better + 原形動詞　　最好……

注意:

使用此片語時, 若以代名詞作主詞時, 經常使用縮寫形, 如: you'd better (你最好)、I'd better (我最好)、he'd better (他最好)、she'd better (她最好)……等。

例: You'd better be on time for the meeting.

  　(你最好準時出席這次的會議。)

  　Henry had not better get drunk again or else his girlfriend
  　would dump him. (╳)

  → Henry had better not get drunk again or else his girlfriend
  　would dump him. (○)

  　(亨利最好不要再喝醉，要不然他女友準會甩了他。)

＊had better與not並用時, not須置於better之後, 而不可置於其前, 即無"had not better"的用法。