在图2-15中，若开关S断开，则此时A点的电位VA为（ ）。 

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SQL Error: select id,body,options from ***_enewstiku where sourceid='30079' and id < 2435305 and id<>'2435305' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='30079' and id > 2435305 and id<>'2435305' order by id asc limit 5