下面哪些是段落写作的特点?
A、A paragraph is a group of sentences that deal with a single topic.
B、The length of paragraphs varies significantly according to text type, but should normally be no less than four or five sentences.
C、Usually (but not always), the first sentence introduces the topic. Other sentences may give definitions, examples, extra information, reasons, restatements and summaries.
D、The parts of the paragraph are linked together by the phrases and conjunctions.