The protoxylem is primary xylem and the metaxylem is secondary xylem.
The protoxylem is primary xylem and the metaxylem is secondary xylem.
The protoxylem is primary xylem and the metaxylem is secondary xylem. A: 正确 B: 错误
The protoxylem is primary xylem and the metaxylem is secondary xylem. A: 正确 B: 错误
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