这是that引导的让步状语从句。
Ungrateful wretches that we are, we try to block out as much as we can.
= Ungrateful wretches as we are, we try to block out as much as we can.
= Ungrateful wretches though we are, we try to block out as much as we can.
= Thoough we are Ungrateful wretches, we try to block out as much as we can.
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