【题目】The woman was about to open the door ____________ she heard a strange sound from inside.
A.as
B.while
C.when
D.then

【答案】C
【解析】句意：当这个妇女正打算开门的时候突然听到里面有一种奇怪的声音。be about to do sth. when…“正打算做……突然…”，根据句意选C。