Thomas Alva Edison didn’t “invent” the light bulb (灯泡), but rather he a 50 –year –old idea, which is not well –known.
A. improved upon
B. take down
C. put up
D. break away
网友回答
(答案→)A. improved upon
B. take down
C. put up
D. break away
解析：句意：鲜为人知是的，爱迪生并没有发明灯炮，而是在其50年前的发明上改进了电灯泡（把灯丝寿命延长到13.5小时）。Improve on/upon超过，改进；take down把……拆卸开；put up张贴，搭建；break away摆脱。