问题
选择题
Thomas Alva Edison didn’t “invent” the light bulb, 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
答案
A
题意：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。