核酸中连接核苷酸的键是（ ）。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='29807' and id < 2419245 and id<>'2419245' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='29807' and id > 2419245 and id<>'2419245' order by id asc limit 5