--- An ant has two stomachs --- one for itself, one for others.
--- Really? Quite interesting. I anything about it.
A. don’t know
B. have known
C. haven’t known
D. didn’t know
网友回答
A. don’t know
B. have known
C. haven’t known
(答案→)D. didn’t know
解析：考查时态。句意：蚂蚁有两个胃——一个给自己，一个为别人。——真的吗？相当有趣儿。关于这个事我一点都不知道。结合语境可知描述的是过去的状态，故用过去时态，选D。