you try to do something beyond what you have already mastered, you will never grow.
A. Since
B. When
C. Though
D. Unless
网友回答
A. Since
B. When
C. Though
(答案→)D. Unless
解析：A．Since 自从，因为，B．When 当…时候，C Though虽然，D．Unless除非，如果不，相当于if not…句意：如果你不努力做超出你已经掌握的东西，你永远不会成长。根据句意选D。