The Internet is a wonderful discovery, of great significance to people’s lives.
A. as is I think.
B. which think it is
C. which I think is
D. as I think
网友回答
A. as is I think.
B. which think it is
(答案→)C. which I think is
D. as I think
解析：考查定语从句，根据句子结构可知，该句为定于从句，先行词是前面一个句子，在从句中作is的主语，I think是插入语，
句意为，英特网是一个伟大的发明，它对人们的生活非常重要。