Apple's share price plummeted today after the company sold two million fewer iPhones over the holiday period than had been predicted.
Apple said it sold a record 47.8 million iPhones in the quarter ending in December, but the average analyst forecast was 50 million units.
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Mr Kim has made two recent visits to China.
The study looked at the development of 422 children over the course of eight years.
The president said they will come into force if China refuses to change its practices.