I am concerned it that I can’t concentrate my work because of headache.
A. of; on
B. of; of
C. about; on
D. about; to
网友回答
A. of; on
B. of; of
(答案→)C. about; on
D. about; to
解析：考查介词：句意：我担心因为工作我不能专心工作。Be concerned about关心，concentrate on 集中精力于……；专心于……选C。