Tom succeeded, for he had made a great and got over plenty of difficulties.
A. progress
B. force
C. energy
D. effort
网友回答
A. progress
B. force
C. energy
(答案→)D. effort
解析：考查名词辨析：A. progress进步B. force力量C. energy精力D. effort努力，句意是;汤姆成功了，因为他做出了努力并克服了很多困难。选D。