Who本身是【疑問詞】或【關係代名詞】, 如果是
「疑問詞」, 可以放在句首, 後面接動詞, 如
Who opened the door?
Who mailed the package?
Who broke the window?
Who當「關係代名詞」時, 前面接名詞, 這個名詞也稱為「先行詞」,
Who引導形容詞子句( 關係子句 ), 補充說明先行詞的訊息。 如
Sunnyah talked to a girl Who she mets yestetday.
Sunnyah is diligent person who always gets to work on time.
Sunnyah need a friend who can help she when she is in trouble.
(子句一定有動詞)