Later forms are more complex, and among these are the sallies , relations of the starfishes, which had long arms and were attached by a long stalk to the sea bed, or to rocks.

• 引言段揭示主题，正文部分对主题分点阐述，结论段对全文归纳总结。同时，无论文章还是段落都要遵循一致性和连贯性的原则。可以说，文章是段落的扩展，段落是文章的缩影。