I speak because I can't keep silent now.
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We know nothing about the deep seabed, and the probe can't go deep. What is the bottom of the sea floor? Is there or may be any life on the seabed at12000m or15000m?
It shows the heart of exploring the unknown seabed, paves the way for seeing Captain Nemo below, and enhances the credibility of the text with numbers.
Ah, I found the book and the sentence. I'm so tired.