As per rule 378.2c, China should have only had two pairs entries in the 2010 World Junior Figure Skating Championships. In the 2009 championship, the Chinese teams placed 8th and 11th, totaling 19 points. A point total of 13 or less is required to enter three pairs into the competition. ISU-- explain? Or am I missing some modification to the rule in a later document?
This reminds me of the speculation before the 2005 World Championships that Viktoria Volchkova was going to be Russia's third entry in the ladies event, even though the country only earned two spots from the previous Worlds, and the reasoning was that Russia (who happened to be the host country) had found some loophole in the rules to allow it to happen. That scenario ended up being completely fictitious, but it actually happened this time!
EDIT 6:15PM: Communication No. 1565 Rule 3c also states that China was entitled to two entries in the pairs competition. Japan earned two spots this year and only used one, and Switzerland used neither of their two earned entries, but never before has a country with one or two entrants been given an additional spot on the basis that other countries were not sending their maximum allotted entries.