A.T. Robertson Commentary John 20:13

"And they say unto her, Woman, why weepest thou? She saith unto them, Because they have taken away my Lord, and I know not where they have laid him." — John 20:13 (ASV)

I do not know (ουκ οιδα). Singular here, not plural as in verse 2, because clearly Mary is alone here. But the problem is the same. She did not see Peter and John at the tomb.