问题补充:
It is said that potato chips by mistake about a hundred years ago.
A. invent
B. invented
C. are invented
D. were invented
答案:
A. invent
B. invented
C. are invented
(答案→)D. were invented
解析:考察时态及语态。句意;据说炸薯片是100年前错误的被发明的。结合语境可知本句描述的是过去的状态,故用一般过去时态。句子主语是动作对象,故用被动语态。选D。