________he starts to do something,he won’t stop until it is finished.
A.Though B.Since
C.Unless D.Once
________he starts to do something,he won’t stop until it is finished.
A.Though B.Since
C.Unless D.Once
D 他一旦开始干一件事,不干完就决不罢休。once此处用作从属连词,表示“一旦”,引导状语从句。