he made up his mind nothing could change it.A. BeforeB. UnlessC. WhenD. Once

问题补充：

he made up his mind, nothing could change it.

A. Before

B. Unless

C. When

D. Once

答案：

A. Before

B. Unless

C. When

(答案→)D. Once

解析：考查连词的用法：A.Before在…前面，B除非，C当…时候，D.once“一旦”，句意是：一旦他下定决心，没有什么可以改变。选D。