设a，b都是有理数，且a＞0，则下列式子所表示的数一定是有理数的是（       ）.[吉林2019]

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SQL Error: select id,body,options from ***_enewstiku where sourceid='27159' and id < 2250238 and id<>'2250238' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='27159' and id > 2250238 and id<>'2250238' order by id asc limit 5