I was surprised to find his article on such an _topic so_.

没有正确的选项,两个空应填：
I was surprised to find his article on such an (exciting) topic so (boring).
我很惊讶地发现,他那篇关于如此激动人心的话题的文章竟如此无趣.
an exciting topic 一个激动人心的话题
his article ...so boring 他的文章...如此无趣
形容某物令人感到（惊奇、激动、有趣...）时,用 ing,形容某人的感受（失望、无聊、惊讶...）时,用 ed.
如：an amazing view,an exciting topic,an interesting picture,
又如：I feel bored,he is frustrated,Tom is interested in...

excited ,boring.