Hi，777fly,
You are really a great help! All your explanations are correct. Thank you very much!
When I saw a 1C service panel picture, I was curious that why it do not has central tank gauge! You solved this question!
1E do has a central tank. However, i'm not sure the "door" is from that tank. From 1E picture, I can see one door in the size and shape of wreckage in the ventral position just under the central tank. But it had no window and no pipes!
I really could not think up a place where is a need to have some pipes go through a "door" in a plane.
Someone has noticed me that the primer used in trident was all green, and the primer on the wreckage was brown, so the wreckage could not be from a trident. Is that correct?