The latest UK official studies show fewer teenagers are now studying foreign languages.
A. what
B. which
C. that
D. Whether
网友回答
A. what
B. which
(答案→)C. that
D. Whether
解析：考查从句，从句fewer teenagers are now studying foreign languages.不缺少成份，动词show，that引导的宾语从句，所以选C