滑动摩擦力是由摩擦面之间的（ ）造成的。

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SQL Error: select id,body,options from ***_enewstiku where sourceid='24897' and id < 2124608 and id<>'2124608' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='24897' and id > 2124608 and id<>'2124608' order by id asc limit 5