design: Fragment genomic DNA into 10 kb pieces using gTube; digest with exonuclease VII to remove 3'-end single-stranded overhangs; repair single-strand breaks, base deletions, oxidation, etc., on DNA strands using a loss repair kit; Perform end repair to generate blunt ends; Ligate barcoded SMRT dumbbell adapters; Digest with exonuclease to remove unligated SMRT dumbbell adapter fragments; Perform secondary purification using 0.45X PB magnetic beads to obtain the sequencing library.