Perfect blunder with perfect tense

[bpositive09]

Present/past perfect Vs Simple past tense:

"The child has drawn a square in the sand" :the square is still there.
"The child drew a square in the sand, but the ocean erased it." : The square is no longer there and thus, simple past.

All good till here.

Now, if I specify an exact time when the child drew the square, and do not mention if it is still there or not, what should be used?

1. The child drew a square in the sand at 4PM.

2. The child drew/has drawn a square in the sand at 4PM and I saw it just now.

3. The child drew/had drawn a square in the sand at 4PM but it was washed away an hour ago.

4. The child had drawn/drew a square in the sand at 4PM but the ocean would have erased it.

5. The child has/had drawn a square in the sand but the ocean would have erased it.

6. The child has drawn/drew a square in the sand at 4PM but the ocean would have erased it


Could you just clear my confusion regarding usage of perfect tense when a time is specified...? Rest all is okay but when specific time is mentioned and the action still has an effect in present, or when nothing is mentioned, I get confused.

[tim]

If it happened at 4PM, that is a specific time in the definite past, so we use "drew". "has drawn" would indicate that the square is a recent creation (in the immediate past, not at 4PM). Let me know if you need further help on this one..