賓語有兩種：動詞和介詞賓語。定語從句是否缺賓語主要看從句中謂語動詞是否是及物動詞，是否該及物動詞後面有賓語，是否介詞後面有賓語。如果及物動詞沒有跟賓語的話，我們就要考慮選用能夠作賓語的關係代詞；如果及物動詞後面有賓語的話，我們就要看看後面是否有介詞，介詞後面是否有賓語：若後面沒有介詞，我們就要考慮用關係副詞了；若有介詞但後面沒有賓語，我們就要選用能夠作介詞賓語的關係代詞了。若從句中的動詞是不及物動詞、又沒有介詞的話，我們就應該考慮用關係副詞了。例如：This is the park which/that we often visit. (visit是及物動詞, 需要有賓語）The factory that/which he works in is two miles away from here. (介詞in後面沒有賓語）The factory where he works is two miles away from here. (work是不及物動詞，從句中沒有介詞）She will never forget the day when she joined the Party is near to my home. (join是及物動詞, 需要有賓語，從句中沒有介詞）