—Where is my pen?—I it on the desk, but I don’t know who it away.A. put; has takenB. put

—Where is my pen?
—I it on the desk, but I don’t know who it away.
A. put; has taken
B. put; took
C. have put; took
D. have put; has taken

(答案→)A. put; has takenB. put; took C. have put; tookD. have put; has taken解析：考察时态。句意：我的钢笔在哪儿？——我放在桌子上了，但是我不知道谁拿走了它。可知前文叙述的是过去发生的动作，下文强调已经完成的动作，故前文用过去时态，下文用完成时态。Put过去时与原形一样，故选A。

哦，回答的不错