---Be careful. You might fall into the river.
---Thank you. I I so close to it．
A. didn’t know; am standing
B. don’t know; am standing
C. didn’t know; was standing
D. didn’t know; would standing
网友回答
A. didn’t know; am standing
B. don’t know; am standing
(答案→)C. didn’t know; was standing
D. didn’t know; would standing
解析：句意：小心。你可能会掉到河里面。——谢谢你。我不知道我站的离它如此近。结合语境可知下文主句描述的是过去发生的动作，从句中描述的是过去正在进行的动作，故主句用一般过去时态，宾语从句用过去进行时态。选C。