I don’t think possible to master a foreign language without much memory work and practice.
A. this
B. that
C. it
D. /
网友回答
A. this
B. that
(答案→)C. it
D. /
解析：考查it做形式宾语的用法：句型：think it +adj+to do，认为做…怎样，句意：我认为没有记忆工作要想掌握一门外语不可能。It指代to master a foreign language，选C。