问题
单项选择题
Researchers all over the world have been seeking for determining how early infancy conceptual thinking is possible.()
A. have been seeking about determining
B. have been seeking to determine about
C. have been seeking to determine
D. have sought to determine
答案
参考答案：C
解析：
因为这一研究始于过去，且仍在延续，所以用过去完成进行时；seek for/after搜寻，寻找，追求；seek to do尝试……，试图……；所以答案为C。